Blog picker popover has the right header color and shows its title.

Fixes #1102 
The grey we were seeing is actually the background of the BlogSelectorViewController.
I'm changing it up so the picker displays a UINavigationController who's root vc is the BlogSelectorViewController.  This way we get the right color + the title which wasn't previously being displayed. 

After:
![ios simulator screen shot jan 31 2014 5 19 00 pm](https://f.cloud.github.com/assets/1435271/2055939/1dcecc4a-8ace-11e3-95d5-f23560f39ab6.png)