DataFrameGroupBy boxplot fails after updating Pandas
The following call to create boxplots of a `DataFrameGroupBy` object used to plot as expected:

```
language_dataset.groupby('bimodal').boxplot(column='age')
```

However, after updating to the current master, it fails with an `AttributeError`:

```
---------------------------------------------------------------------------
AttributeError                            Traceback (most recent call last)
<ipython-input-11-369e94355e02> in <module>()
----> 1 language_dataset.groupby('bimodal').boxplot(column='age');

/Library/Python/2.7/site-packages/pandas-0.13.1_213_gc174c3d-py2.7-macosx-10.9-intel.egg/pandas/tools/plotting.pyc in boxplot_frame_groupby(grouped, subplots, column, fontsize, rot, grid, figsize, **kwds)
   2313         for (key, group), ax in zip(grouped, axes):
   2314             d = group.boxplot(ax=ax, column=column, fontsize=fontsize,
-> 2315                               rot=rot, grid=grid, figsize=figsize, **kwds)
   2316             ax.set_title(com.pprint_thing(key))
   2317             ret[key] = d

/Library/Python/2.7/site-packages/pandas-0.13.1_213_gc174c3d-py2.7-macosx-10.9-intel.egg/pandas/core/frame.pyc in boxplot(self, column, by, ax, fontsize, rot, grid, **kwds)
   4841     import matplotlib.pyplot as plt
   4842     ax = plots.boxplot(self, column=column, by=by, ax=ax,
-> 4843                        fontsize=fontsize, grid=grid, rot=rot, **kwds)
   4844     plt.draw_if_interactive()
   4845     return ax

/Library/Python/2.7/site-packages/pandas-0.13.1_213_gc174c3d-py2.7-macosx-10.9-intel.egg/pandas/tools/plotting.pyc in boxplot(data, column, by, ax, fontsize, rot, grid, figsize, **kwds)
   2000         if ax is None:
   2001             ax = _gca()
-> 2002         fig = ax.get_figure()
   2003         data = data._get_numeric_data()
   2004         if columns:

AttributeError: 'numpy.ndarray' object has no attribute 'get_figure'
```

Running Python 2.7.5 on OS X 10.9.2. Numpy version 1.9.0.
