ENH:Implement .plot() for OLS Regression
I think the `.plot()` should also apply to OLS regression from `pandas.stats.api import ols`

Let say I have some points and I do

`regression = ols(y=df['Y_VALUES'], x=df[['X_VALUES']])`
So if I type
`print (regression)`
it gives me a summary of the data.

What I am suggesting is that if I type something like:

```
regression.plot()
plt.show()
```

It should give me a scatter plot with the best fit line.
