Added support for blank button labels in theming code

Signed-off-by: Darren Ehlers <me@darrenehlers.com>
Added runOnMainThreadWithoutDeadlocking call to runAfterDelay:block: method

- Added runOnMainThreadWithoutDeadlocking call to runAfterDelay:block: method
- Added performBlock: call to deleteAllWithCompletion:
- Updated DNModelWatchFetchedObjects refreshWatch/startWatch
- Updated podspec version

Signed-off-by: Darren Ehlers <me@darrenehlers.com>