TalkBack functions properly with MessageList items, as well as
"reply," "reply-all," and "forward" buttons while viewing messages.
It is now also possible to switch accounts using only a dpad
or trackball. Finally, EditText fields in account setup also work
with TalkBack now.
Checkmarks don't work with Talkback, but this I have confirmed and
reported it as frameworks bug.
Change-Id: I7f72682a517eef4fa122241c675026fe7997ac64