Set post settings tableview as grouped

Fixed #1917

Grouped table views don't allow section heights of 0.0f so I had to do a simple hack with content inset. Is that OK?

The result looks good on both iPhone and iPad:
![ios simulator screen shot 16 jul 2014 01 49 38 pm](https://cloud.githubusercontent.com/assets/820515/3598383/04b1ca5a-0ce2-11e4-8bc7-25dc007ce83d.png)
![ios simulator screen shot 16 jul 2014 01 57 46 pm](https://cloud.githubusercontent.com/assets/820515/3598384/04b5d762-0ce2-11e4-90b1-c8594c6656e3.png)