Datetime formatting for year < 1900
```
In [1]: rng = date_range('1/1/1800', '1/1/2000')

In [2]: rng
Out[2]: 
<class 'pandas.tseries.index.DatetimeIndex'>
freq: <1 Day>, timezone: None
[1800-01-01 00:00:00, ..., 2000-01-01 00:00:00]
length: 73049

In [3]: ts = Series(randn(len(rng)), index=rng)

In [4]: ts
Out[4]: ---------------------------------------------------------------------------
ValueError                                Traceback (most recent call last)
/Users/wesm/code/pandas/<ipython-input-4-a03e77341a8b> in <module>()
----> 1 ts

/Users/wesm/code/repos/ipython/IPython/core/displayhook.pyc in __call__(self, result)
    236             self.start_displayhook()
    237             self.write_output_prompt()
--> 238             format_dict = self.compute_format_data(result)
    239             self.write_format_data(format_dict)
    240             self.update_user_ns(result)

/Users/wesm/code/repos/ipython/IPython/core/displayhook.pyc in compute_format_data(self, result)
    148             MIME type representation of the object.
    149         """
--> 150         return self.shell.display_formatter.format(result)
    151 
    152     def write_format_data(self, format_dict):

/Users/wesm/code/repos/ipython/IPython/core/formatters.pyc in format(self, obj, include, exclude)
    124                     continue
    125             try:
--> 126                 data = formatter(obj)
    127             except:
    128                 # FIXME: log the exception

/Users/wesm/code/repos/ipython/IPython/core/formatters.pyc in __call__(self, obj)
    445                 type_pprinters=self.type_printers,
    446                 deferred_pprinters=self.deferred_printers)
--> 447             printer.pretty(obj)
    448             printer.flush()
    449             return stream.getvalue()

/Users/wesm/code/repos/ipython/IPython/lib/pretty.pyc in pretty(self, obj)
    358                             if callable(meth):
    359                                 return meth(obj, self, cycle)
--> 360             return _default_pprint(obj, self, cycle)
    361         finally:
    362             self.end_group()

/Users/wesm/code/repos/ipython/IPython/lib/pretty.pyc in _default_pprint(obj, p, cycle)
    478     if getattr(klass, '__repr__', None) not in _baseclass_reprs:
    479         # A user-provided repr.
--> 480         p.text(repr(obj))
    481         return
    482     p.begin_group(1, '<')

/Users/wesm/code/pandas/pandas/core/series.pyc in __repr__(self)
    699                     else fmt.print_config.max_rows)
    700         if len(self.index) > max_rows:
--> 701             result = self._tidy_repr(min(30, max_rows - 4))
    702         elif len(self.index) > 0:
    703             result = self._get_repr(print_header=True,

/Users/wesm/code/pandas/pandas/core/series.pyc in _tidy_repr(self, max_vals)
    712         num = max_vals // 2
    713         head = self[:num]._get_repr(print_header=True, length=False,
--> 714                                     name=False)
    715         tail = self[-(max_vals - num):]._get_repr(print_header=False,
    716                                                   length=False,

/Users/wesm/code/pandas/pandas/core/series.pyc in _get_repr(self, name, print_header, length, na_rep, float_format)
    762                                         length=length, na_rep=na_rep,
    763                                         float_format=float_format)
--> 764         return formatter.to_string()
    765 
    766     def __str__(self):

/Users/wesm/code/pandas/pandas/core/format.pyc in to_string(self)
     98             return ''
     99 
--> 100         fmt_index, have_header = self._get_formatted_index()
    101         fmt_values = self._get_formatted_values()
    102 

/Users/wesm/code/pandas/pandas/core/format.pyc in _get_formatted_index(self)
     84         else:
     85             have_header = index.name is not None
---> 86             fmt_index = index.format(name=True)
     87         return fmt_index, have_header
     88 

/Users/wesm/code/pandas/pandas/core/index.pyc in format(self, name)
    333                 if dt.time() != zero_time or dt.tzinfo is not None:
    334                     return header + ['%s' % x for x in self]
--> 335                 result.append(dt.strftime("%Y-%m-%d"))
    336             return header + result
    337 

ValueError: year=1800 is before 1900; the datetime strftime() methods require year >= 1900
```
