Settings observer doesn't work if a setting is modified in another
process, hence we instead register a receiver which listens for a signal
from the settings process that the rotation preference has changed.
Change-Id: I570e3c67bb64a32347e84ca00a8ac31d9010eac3
This CL adds a Settings activity along with the code needed to provide
a "Allow Rotation" setting to all phones and tablets. This setting is
set to false for phones and true for tablets. On changing the setting
from unlocked to locked, the launcher (and the Settings activity)
will get locked to the orientation the user was in when he disabled
"Allow Rotation". This is consistent with how the natural rotation
feature of Android works.
Change-Id: I8a1c59d1fa0bb9262530cad96e0a9bdbab0d9344
