Sjang92/advanced settings feedback

@jrbl  @njdup

There were no validations being done in Studio's course advanced settings tab. 
Now course instructors receive feed back as a list of settings changes that has formatting/value errors.

![screen shot 2014-07-16 at 4 13 13 pm](https://cloud.githubusercontent.com/assets/3598201/3606958/e8fe92b8-0d3e-11e4-8fe6-b861b0a8b3d4.png)

Can this be shortened in such a way that it can fit on one line? For example, something like:
```
"""
Update metadata descriptor in modulestore from key_values.
"""
```

Tools that manipulate pydoc do nice things if the first line of a docstring is only one line long, much like the 50 character summary line on git commit messages.