Added "drivers" to cells that defined ONOS_APPS.

Change-Id: I8e7cbea037ea09504662fb17ef328b547d21050a
diff --git a/tools/test/cells/beast b/tools/test/cells/beast
index aa34e51..6afd61d 100644
--- a/tools/test/cells/beast
+++ b/tools/test/cells/beast
@@ -15,4 +15,4 @@
 export OC6=10.254.1.206
 export OC7=10.254.1.207
 
-export ONOS_APPS=null,intentperf
+export ONOS_APPS="drivers,null,intentperf"