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>

Conflicts:

	res/values/cm_strings.xml
Settings: Display up caret for Status and ChooseAccountActivity

Change-Id: Ia9d51b53df8a3eb4c1b9dee1aeefb0b74eac0fde