Added "drivers" to cells that defined ONOS_APPS.

Change-Id: I8e7cbea037ea09504662fb17ef328b547d21050a
diff --git a/tools/test/cells/beast-1 b/tools/test/cells/beast-1
index c6e45e4..698eded 100644
--- a/tools/test/cells/beast-1
+++ b/tools/test/cells/beast-1
@@ -9,4 +9,4 @@
 # Use the 1G NICs for external access
 export OC1=10.254.1.201
 
-export ONOS_APPS=null,intentperf
+export ONOS_APPS="drivers,null,intentperf"