improved error message for invalid chart types
Closes #9400

`pd.Series([2,3,4]).plot("quiver")` now gives an improved error message:

```
Users/ch/miniconda/envs/pd_dev34/lib/python3.4/site-packages/pandas/tools/plotting.py in _plot(data, x, y, subplots, ax, kind, **kwds)
   2269         klass = _plot_klass[kind]
   2270     else:
-> 2271         raise ValueError(invalid_ct_fmtstr % kind)
   2272 
   2273     from pandas import DataFrame

ValueError: 'quiver' is not a valid chart type
```

instead of:

```
/Users/ch/miniconda/envs/sci33/lib/python3.3/site-packages/pandas/tools/plotting.py in _plot(data, x, y, subplots, ax, kind, **kwds)
   2267         klass = _plot_klass[kind]
   2268     else:
-> 2269         raise ValueError('Invalid chart type given %s' % kind)
   2270 
   2271     from pandas import DataFrame

ValueError: Invalid chart type given quiver
```
