[ONOS-4588] Separate optical driver from "default" driver bundle

Note: If you're using optical devices currently in "default" driver bundle,
(LINC-OE, Calient fiber switch, ECI devices, OpLink ROADM)

you'll need to load the driver/app "drivers.optical" in adition to default drivers

a) Add to cell definition
 export ONOS_APPS=${ONOS_APPS},drivers.optical

b) Activate after starting ONOS
 onos> app activate org.onosproject.drivers.optical

Change-Id: I126c09bebc816d11b4700a80e7a36a8e6c3e1b49
diff --git a/tools/test/cells/single_optical b/tools/test/cells/single_optical
index 6bbe176..ac4fc27 100644
--- a/tools/test/cells/single_optical
+++ b/tools/test/cells/single_optical
@@ -4,4 +4,4 @@
 export OC1=""
 export OCN=""
-export ONOS_APPS="drivers,openflow,fwd,proxyarp,mobility,optical"
+export ONOS_APPS="drivers,drivers.optical,openflow,fwd,proxyarp,mobility,optical"