Add SELinux rules for service_manager.

Add a service_mananger class with the verb add.
Add a type that groups the services for each of the
processes that is allowed to start services in service.te
and an attribute for all services controlled by the service
manager. Add the service_contexts file which maps service
name to target label.

Bug: 12909011
Change-Id: I017032a50bc90c57b536e80b972118016d340c7d
diff --git a/mediaserver.te b/mediaserver.te
index 439315f..e4d5a23 100644
--- a/mediaserver.te
+++ b/mediaserver.te
@@ -78,3 +78,5 @@
 
 # Connect to tee service.
 allow mediaserver tee:unix_stream_socket connectto;
+
+allow mediaserver mediaserver_service:service_manager add;