cm: add selective based spn (2/2)

* patch set 1 to 7 doesn't fix the problem, it bruce forces the spn
list to ALL DEVICES.
* this change and http://review.cyanogenmod.org/#/c/57393/
will attack the problem at lowest level, customized it for speed
and memory.
*  the best part is that it handles letters and exit the
function when it find a letter in the response from ril.

Change-Id: Ia63309acf38617e68b98ff1068463a942fa793df
cm versioning: Empty keys == default keys

Don't assume the path to the signing key is the default, it can
be empty and have the same meaning...

Change-Id: Id545d6436e9f21d6b62eec5a317ea7665190f104
cm: Set perms on a few additional paths

Change-Id: I128220850a21bef261ff735ff51e8b715391c37d