Create test owner for presence service

This owner changes properties periodically so we can test out the PS's handling
of property changes.  To execute, run Sugar and then make sure that the D-Bus
address is the one sugar is using (get it from ~/.sugar/default/session.info).
Then run:

build/bin/sugar-presence-service X

where X is a number 1 -> 9 inclusive.  It will generate fake buddy info for that
test buddy and then start up a presence service for that buddy, changing a random
property of the buddy every 10 seconds.

services/presence/sugar-presence-service

@@ -32,4 +32,13 @@ import presenceservice
 
 logging.info('Starting presence service')
 
-presenceservice.main()
+test=0
+if len(sys.argv) > 1:
+    try:
+        test = int(sys.argv[1])
+    except ValueError:
+        logging.debug("Bad test user number.")
+    if test < 1 or test > 10:
+        logging.debug("Bad test user number.")
+
+presenceservice.main(test)