Plot does not work in the 10 Minutes tutorial
The following codes from [10 Minutes to pandas](http://pandas.pydata.org/pandas-docs/stable/10min.html) could not be run properly.

```python
In [135]: ts = pd.Series(np.random.randn(1000), index=pd.date_range('1/1/2000', periods=1000))
In [136]: ts = ts.cumsum()
In [137]: ts.plot()
```
#### Problem description

It gives error as follows. Is that caused by some dependency problem or other issues? Thanks.

```python
---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
<ipython-input-154-72917dc50e90> in <module>()
      3 ts = ts.cumsum()
      4 
----> 5 ts.plot()

/home/myubuntu/anaconda2/envs/tensorflow3/lib/python3.5/site-packages/pandas/tools/plotting.py in __call__(self, kind, ax, figsize, use_index, title, grid, legend, style, logx, logy, loglog, xticks, yticks, xlim, ylim, rot, fontsize, colormap, table, yerr, xerr, label, secondary_y, **kwds)
   3597                            colormap=colormap, table=table, yerr=yerr,
   3598                            xerr=xerr, label=label, secondary_y=secondary_y,
-> 3599                            **kwds)
   3600     __call__.__doc__ = plot_series.__doc__
   3601 

/home/myubuntu/anaconda2/envs/tensorflow3/lib/python3.5/site-packages/pandas/tools/plotting.py in plot_series(data, kind, ax, figsize, use_index, title, grid, legend, style, logx, logy, loglog, xticks, yticks, xlim, ylim, rot, fontsize, colormap, table, yerr, xerr, label, secondary_y, **kwds)
   2671                  yerr=yerr, xerr=xerr,
   2672                  label=label, secondary_y=secondary_y,
-> 2673                  **kwds)
   2674 
   2675 

/home/myubuntu/anaconda2/envs/tensorflow3/lib/python3.5/site-packages/pandas/tools/plotting.py in _plot(data, x, y, subplots, ax, kind, **kwds)
   2467         plot_obj = klass(data, subplots=subplots, ax=ax, kind=kind, **kwds)
   2468 
-> 2469     plot_obj.generate()
   2470     plot_obj.draw()
   2471     return plot_obj.result

/home/myubuntu/anaconda2/envs/tensorflow3/lib/python3.5/site-packages/pandas/tools/plotting.py in generate(self)
   1041         self._compute_plot_data()
   1042         self._setup_subplots()
-> 1043         self._make_plot()
   1044         self._add_table()
   1045         self._make_legend()

/home/myubuntu/anaconda2/envs/tensorflow3/lib/python3.5/site-packages/pandas/tools/plotting.py in _make_plot(self)
   1724                              stacking_id=stacking_id,
   1725                              is_errorbar=is_errorbar,
-> 1726                              **kwds)
   1727             self._add_legend_handle(newlines[0], label, index=i)
   1728 

/home/myubuntu/anaconda2/envs/tensorflow3/lib/python3.5/site-packages/pandas/tools/plotting.py in _ts_plot(cls, ax, x, data, style, **kwds)
   1762         ax._plot_data.append((data, cls._kind, kwds))
   1763 
-> 1764         lines = cls._plot(ax, data.index, data.values, style=style, **kwds)
   1765         # set date formatter, locators and rescale limits
   1766         format_dateaxis(ax, ax.freq)

/home/myubuntu/anaconda2/envs/tensorflow3/lib/python3.5/site-packages/pandas/tools/plotting.py in _plot(cls, ax, x, y, style, column_num, stacking_id, **kwds)
   1739             cls._initialize_stacker(ax, stacking_id, len(y))
   1740         y_values = cls._get_stacked_values(ax, stacking_id, y, kwds['label'])
-> 1741         lines = MPLPlot._plot(ax, x, y_values, style=style, **kwds)
   1742         cls._update_stacker(ax, stacking_id, y)
   1743         return lines

/home/myubuntu/anaconda2/envs/tensorflow3/lib/python3.5/site-packages/pandas/tools/plotting.py in _plot(cls, ax, x, y, style, is_errorbar, **kwds)
   1359             else:
   1360                 args = (x, y)
-> 1361             return ax.plot(*args, **kwds)
   1362 
   1363     def _get_index_name(self):

/home/myubuntu/anaconda2/envs/tensorflow3/lib/python3.5/site-packages/matplotlib/__init__.py in inner(ax, *args, **kwargs)
   1817                     warnings.warn(msg % (label_namer, func.__name__),
   1818                                   RuntimeWarning, stacklevel=2)
-> 1819             return func(ax, *args, **kwargs)
   1820         pre_doc = inner.__doc__
   1821         if pre_doc is None:

/home/myubuntu/anaconda2/envs/tensorflow3/lib/python3.5/site-packages/matplotlib/axes/_axes.py in plot(self, *args, **kwargs)
   1381 
   1382         for line in self._get_lines(*args, **kwargs):
-> 1383             self.add_line(line)
   1384             lines.append(line)
   1385 

/home/myubuntu/anaconda2/envs/tensorflow3/lib/python3.5/site-packages/matplotlib/axes/_base.py in add_line(self, line)
   1701             line.set_clip_path(self.patch)
   1702 
-> 1703         self._update_line_limits(line)
   1704         if not line.get_label():
   1705             line.set_label('_line%d' % len(self.lines))

/home/myubuntu/anaconda2/envs/tensorflow3/lib/python3.5/site-packages/matplotlib/axes/_base.py in _update_line_limits(self, line)
   1723         Figures out the data limit of the given line, updating self.dataLim.
   1724         """
-> 1725         path = line.get_path()
   1726         if path.vertices.size == 0:
   1727             return

/home/myubuntu/anaconda2/envs/tensorflow3/lib/python3.5/site-packages/matplotlib/lines.py in get_path(self)
    936         """
    937         if self._invalidy or self._invalidx:
--> 938             self.recache()
    939         return self._path
    940 

/home/myubuntu/anaconda2/envs/tensorflow3/lib/python3.5/site-packages/matplotlib/lines.py in recache(self, always)
    623                 x = ma.asarray(xconv, np.float_).filled(np.nan)
    624             else:
--> 625                 x = np.asarray(xconv, np.float_)
    626             x = x.ravel()
    627         else:

/home/myubuntu/anaconda2/envs/tensorflow3/lib/python3.5/site-packages/numpy/core/numeric.py in asarray(a, dtype, order)
    480 
    481     """
--> 482     return array(a, dtype, copy=False, order=order)
    483 
    484 def asanyarray(a, dtype=None, order=None):

TypeError: float() argument must be a string or a number, not 'Period'
```

#### Output of ``pd.show_versions()``

<details>
# Paste the output here pd.show_versions() here
INSTALLED VERSIONS
------------------
commit: None
python: 3.5.2.final.0
python-bits: 64
OS: Linux
OS-release: 3.16.0-38-generic
machine: x86_64
processor: x86_64
byteorder: little
LC_ALL: None
LANG: en_US.UTF-8
LOCALE: en_US.UTF-8

pandas: 0.19.1
nose: None
pip: 9.0.1
setuptools: 27.2.0
Cython: None
numpy: 1.11.2
scipy: 0.18.1
statsmodels: None
xarray: None
IPython: 5.1.0
sphinx: None
patsy: None
dateutil: 2.6.0
pytz: 2016.10
blosc: None
bottleneck: None
tables: None
numexpr: None
matplotlib: 1.5.3
openpyxl: None
xlrd: None
xlwt: None
xlsxwriter: None
lxml: None
bs4: None
html5lib: None
httplib2: None
apiclient: None
sqlalchemy: None
pymysql: None
psycopg2: None
jinja2: 2.8
boto: None
pandas_datareader: None
</details>
