Fixes for post/save button on new editor

Fixes https://github.com/wordpress-mobile/WordPress-iOS-Editor/issues/4

* Updates the shared pod to 0.1.2 (includes semibold font)
* Removes no-longer-needed UIBarButtonItem hack
* Primary navbar button on new editor is now semibold.
* Adjusts color/alpha for UIBarButtonItem's UIControlStateDisabled state app-wide

/cc @diegoreymendez