Cleaned up header inclusions. Removed which are no longer in use and replaced AboutViewController.h with WordPressAppDelegate.h since it is required after removing AboutViewController.h
Added CategoryService to house all methods from original NSMO
Refactored to use CategoryService rather than class methods on Category
Refactored CategoryService to place remote calls in a separate class
Make sure to set server's category ID on local Category entity
Be nicer if the NSManagedObjectID is nil - just return nil
Make parent Category 0 if not set and convert incoming ID to a NSNumber
Get rid of the background context in CategoryService

If a background context is required for merging, than a new instance of CategoryService should be created in the calling code using a background context.
Fixed a misspelled class name in the Core Data model for Category
Cleaning up extraneous comments left from previous architecture
Calling super awakeFromFetch in NSMO subclasses
Added missing dealloc-like operations to didTurnIntoFault
Sorted classes alphabetically under Models
Added missing super calls for didTurnIntoFault
Added missing dealloc-like operations to didTurnIntoFault
Set properties to nil through accessor methods rather than direct
Remove app update check - no longer necessary under iOS 7

Yay less crap in the App Delegate!
Additional app delegate cleanup - unused code and extraneous imports
Don't show blog picker if currently viewing blog.
Drop unused checkWPcomAuthentication

Fixes #688