Remove macro IS_IOS7
Remove EditPostViewController nibs for iOS 6

But don’t rename the iOS 7 one, as it may cause problems with future builds (caching issue?)
Merge branch 'develop' of github.com:wordpress-mobile/WordPress-iOS into issue/639-weak-views

Conflicts:
	WordPress/Classes/EditPostViewController.m
	WordPress/Classes/NotificationsCommentDetailViewController.m
	WordPress/Classes/WPInfoView.h
	WordPress/Classes/WPInfoView.xib
Merge pull request #783 from wordpress-mobile/issue/599-removeios6

#599 Remove IS_IOS7 macro