Don't crash on posts without avatars
Fixed time zone calculation on reader dates
Fixed avatar loading

Code was in the wrong place and only fetching gravatars on posts with
images
Clear delegate on dealloc for post detail
Use options instead of CSS for text style

With this, we should be able to cache the attribute string in the post
object, without storing styling information in the models
Moves some synching logic from the ReaderPostViewController to the model.
Changes ReaderPostViewController to inherit from WPTableViewController instead of WPRefreshViewController.
Updates WPTableViewController and WPTableViewControllerSubclass to support options and features needed by the reader posts list.
Merge branch 'reader' of https://github.com/wordpress-mobile/WordPress-iOS into reader

Conflicts:
	WordPress/Classes/ReaderPostsViewController.m