Settings: Mock SMS (3/4)

This change brings the possibility of simulate the reception of SMS on real devices.
This change includes the settings to enable/disable the mock SMS feature.

Ported from http://review.cyanogenmod.org/#/c/23018

Patchset 2/3: Rebased

Change-Id: I8818995147c41db261d9c9506c1741ed99ef581e
Signed-off-by: Jorge Ruesga <jorge@ruesga.com>
Settings: Display up caret for Status and ChooseAccountActivity

Change-Id: Ia9d51b53df8a3eb4c1b9dee1aeefb0b74eac0fde
Performance settings: remove dithering setting

This setting has no effect in CM10.2, as SurfaceFlinger has now been
taught to automatically Do The Right Thing [tm] with regards to deciding
when to enable surface dithering.

Change-Id: I67fba732440507c1209f2793d826badd4b4d34d5
merge changes from CyanogenMod 10.2 into local branch