Allow SELinuxPolicyInstallReceiver to update new policy files.

Include selinux_version and mac_permissions.xml files in
the list of policy related files that can be updated via
this mechanism.

Change-Id: I16e2d85aab0f90be331ca455328474006950722c
Signed-off-by: rpcraig <rpcraig@tycho.ncsc.mil>