Removes obsolete reference to detail controller.

Closes #2108
Merge branch 'develop' of github.com:wordpress-mobile/WordPress-iOS into issues/2108-remove-ref-to-detail

Conflicts:
	WordPress/Classes/ViewRelated/Reader/ReaderPostsViewController.m
Merge pull request #2190 from wordpress-mobile/issues/2108-remove-ref-to-detail

Removes obsolete reference to detail controller.