Added new ShowFeedback SimpleProperty (default true). This allows user
to specify if they want visual feedback to be shown for a button that
has an image.

Change-Id: I57371642955c025b24f47ad2dc07684556381bcd
Change style changes to camelCase, fixes Button mock component issue
where Shape changes don't work in Firefox. Also gets past an asset in
GWT dev mode.

Change-Id: I324de1d62f4a91c5c2d29ad7fb675aafaf426314
Upgrade:
  - Upgrade to twitter4j version 3.0.3 which is fully compatible with Twitter API 1.1, in which Search is now a REST endpoint.
Fixes:
  - Authentication problems with stored tokens when re-starting the app
  - Authentication problems with Twitter service not finishing the auth process successfully
  - Adding checks to methods to make sure the user is authenticated and avoiding crashing the app if not

Change-Id: Ifdbdf35f792553fe5325e10d5dac3127900299fc