Added text labels to moderation buttons.

Clearer moderation icons.
Added ability for WPContentView to display the date in the 'byView'.
Added a vertically stacked UIButton subclass to use for the moderation buttons.
restored `addActionButton` method back to its original state.
Added alert prompt to be shown when a comment couldn't be moderated.
removed now unused methods from `ContentActionButton`
Adjusted button size back to 48 pixels.
Added 'Un' toggle states for the Trash and Spam buttons.
Added action sheet delete prompt for trashing a comment since it is destructive.

Added error alert prompt if moderation fails in `CommentViewController`
Removed now unused icons.
Use correct name for new spam icon.
Removes obsolete reference to detail controller.

Closes #2108
Code cleanup: Use `setAccessibilityLabel` method instead of dot notation so the code reads easier.
Removed unnecessary else clause when updating a button's status.
Added `updateStateOfActionButton: toState:` in case we want to set the state of an individual button.
Added an enum for a note's comment actions.
WPNoResultsView: Button hidden by default
Notifications: Prevents showing Back button Title
ReaderCommentPublisher: Updates init signature
Make sure account is valid when merging topics

Rolls back changes in 8893587 that created an issue with the reader when noone was logged in.