Create a new location for /data policy files

Adding a new location for policy files under
/data, the new location is /data/security. The
new location is used before attempting to use
any other location.
This requires a new directory to be created by
the init script and an update to the location of
the property_contexts file for property service.

Change-Id: I955a722ac3e51fa6c1b97201b8bdef3f601cf09d