Mark READ_SETTINGS and WRITE_SETTINGS permission as dangerous

Malicious apps can silently request these permissions and use them to
manipulate existing home screen shortcuts.

http://www.fireeye.com/blog/technical/2014/04/occupy_your_icons_silently_on_android.html

Change-Id: I7a40dcae575730fd9b5b190b1e67c1cec7057b02
Signed-off-by: Dirk Rettschlag <dirk.rettschlag@gmail.com>