Add WRITE_MEDIA_STORAGE permission

This fixes the issue where the images/pics are not
deleted from the android external 'SD Card' as android does not
allow writing to the external 'SD Card' with just the
WRITE_EXTERNAL_STORAGE permission.

Requires : https://gerrit.slimroms.net/#/c/2723

Change-Id: I34377160b8b8677abc3506d8aca72166b4129425