Framework: Fix button label toasts when layout is RTL

Google have decided to set their gravity "relatively", while they measure only from the left.
The result? Toasts appearing in the wrong side of the screen.

Change-Id: If5e9d5fc2751fbef3eb058b241168fb9d8bf4b98
Merge "Framework: Fix button label toasts when layout is RTL" into cm-10.1