title: ts.plot() and dataFrame.plot() throwing error: " NameError: name '_converter' is not defined"
body: <p>When running <code>plot()</code> method of a dataframe or series, python is throwing an error. Last line of the error is <code>NameError: name '_converter' is not defined</code></p>
  
  <p>I am using Python 3.6 and all other functionalities are working as expected so unsure what might be causing this.</p>
  
  <p>Below is a code sample that causes the issue, and below that is the error that results.</p>
  
  <pre><code>import pandas as pd
  import numpy as np
  import matplotlib
  import matplotlib.pyplot as plt
  
  ts = pd.Series(np.random.randn(1000), index=pd.date_range('1/1/2000', periods=1000))
  ts = ts.cumsum()
  ts.plot()
  </code></pre>
  
  <p>The error being returned is shown below:</p>
  
  <pre><code>NameError                                 Traceback (most recent call last)
  &lt;ipython-input-336-8fe4bd433d4d&gt; in &lt;module&gt;()
  ----&gt; 1 ts.plot()
        2 
        3 plt.plot(ts)
  
  c:\users\fguih\appdata\local\programs\python\python36\lib\site-packages\pandas\plotting\_core.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)
     2501                            colormap=colormap, table=table, yerr=yerr,
     2502                            xerr=xerr, label=label, secondary_y=secondary_y,
  -&gt; 2503                            **kwds)
     2504     __call__.__doc__ = plot_series.__doc__
     2505 
  
  c:\users\fguih\appdata\local\programs\python\python36\lib\site-packages\pandas\plotting\_core.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)
     1925                  yerr=yerr, xerr=xerr,
     1926                  label=label, secondary_y=secondary_y,
  -&gt; 1927                  **kwds)
     1928 
     1929 
  
  c:\users\fguih\appdata\local\programs\python\python36\lib\site-packages\pandas\plotting\_core.py in _plot(data, x, y, subplots, ax, kind, **kwds)
     1725                             pass
     1726                 data = series
  -&gt; 1727         plot_obj = klass(data, subplots=subplots, ax=ax, kind=kind, **kwds)
     1728 
     1729     plot_obj.generate()
  
  c:\users\fguih\appdata\local\programs\python\python36\lib\site-packages\pandas\plotting\_core.py in __init__(self, data, **kwargs)
      929 
      930     def __init__(self, data, **kwargs):
  --&gt; 931         MPLPlot.__init__(self, data, **kwargs)
      932         if self.stacked:
      933             self.data = self.data.fillna(value=0)
  
  c:\users\fguih\appdata\local\programs\python\python36\lib\site-packages\pandas\plotting\_core.py in __init__(self, data, kind, by, subplots, sharex, sharey, use_index, figsize, grid, legend, rot, ax, fig, title, xlim, ylim, xticks, yticks, sort_columns, fontsize, secondary_y, colormap, table, layout, **kwds)
       98                  table=False, layout=None, **kwds):
       99 
  --&gt; 100         _converter._WARN = False
      101         self.data = data
      102         self.by = by
  
  NameError: name '_converter' is not defined
  </code></pre>