DevTools: Mock SMS (4/4)

This change brings the possibility of simulate the reception of SMS on real devices.
This change includes an activity to simulate the sending of a SMS throught the
mock SMS feature

Ported from http://review.cyanogenmod.org/#/c/23034/

Change-Id: I0e843a6c5ac7c69b1bc1dff156e1f14301674ca9
Signed-off-by: Jorge Ruesga <jorge@ruesga.com>
Dev Tools: Hide the icon