Misleading Documentation for panel.tz_localize()
#### Code Sample, a copy-pastable example if possible

``` python
>>> panel.tz_localize(tz = pytz.UTC, axis=1)
>>> pp.pprint(panel.axes[1].tzinfo)
```

``` python
[Index([u'ddhm', u'ffhm', u'nnhv', u'pshv', u'tahv', u'uuhv', u'rrhs'], dtype='object'),
 DatetimeIndex(['2016-03-09 12:05:05'], dtype='datetime64[ns]', name=u'date', freq=None),
 DatetimeIndex(['2016-03-09 13:00:00', '2016-03-09 14:00:00',
               '2016-03-09 15:00:00', '2016-03-09 16:00:00',
               '2016-03-09 17:00:00', '2016-03-09 18:00:00',
               '2016-03-09 19:00:00', '2016-03-09 20:00:00',
               '2016-03-09 21:00:00', '2016-03-09 22:00:00',
               ...
               '2016-03-19 03:00:00', '2016-03-19 04:00:00',
               '2016-03-19 05:00:00', '2016-03-19 06:00:00',
               '2016-03-19 07:00:00', '2016-03-19 08:00:00',
               '2016-03-19 09:00:00', '2016-03-19 10:00:00',
               '2016-03-19 11:00:00', '2016-03-19 12:00:00'],
              dtype='datetime64[ns]', name=u'forecast', length=240, freq=None)]
None
```
#### Expected Output

``` python
[Index([u'ddhm', u'ffhm', u'nnhv', u'pshv', u'tahv', u'uuhv', u'rrhs'], dtype='object'),
 DatetimeIndex(['2016-03-09 12:05:05+00:00'], dtype='datetime64[ns, UTC]', name=u'date', freq=None),
 DatetimeIndex(['2016-03-09 13:00:00', '2016-03-09 14:00:00',
               '2016-03-09 15:00:00', '2016-03-09 16:00:00',
               '2016-03-09 17:00:00', '2016-03-09 18:00:00',
               '2016-03-09 19:00:00', '2016-03-09 20:00:00',
               '2016-03-09 21:00:00', '2016-03-09 22:00:00',
               ...
               '2016-03-19 03:00:00', '2016-03-19 04:00:00',
               '2016-03-19 05:00:00', '2016-03-19 06:00:00',
               '2016-03-19 07:00:00', '2016-03-19 08:00:00',
               '2016-03-19 09:00:00', '2016-03-19 10:00:00',
               '2016-03-19 11:00:00', '2016-03-19 12:00:00'],
              dtype='datetime64[ns]', name=u'forecast', length=240, freq=None)]
<UTC>
```
#### output of `pd.show_versions()`

http://paste.pound-python.org/show/zeZJO5S6OCJJ3Ohk3UWf/

using `panel = panel.tz_locaize()`fixes it, but there is no information about inplace operation or a return value @ http://pandas.pydata.org/pandas-docs/stable/generated/pandas.Panel.tz_localize.html 
