ONOS-1328 Converted ONOS features to apps.

ONOS_FEATURES env. var is now deprecated!

Cells are expected to use ONOS_APPS env. var to tailor which builtin apps should be activated by default.  All builtin apps are installed by default, but can be uninstalled if desired.

Cleaned up cell definitions accordingly.

Change-Id: If3bb4691a73543a69197f4bf1855c8368f558450
diff --git a/tools/test/cells/single_optical b/tools/test/cells/single_optical
index 9eb613c..1785bfc 100644
--- a/tools/test/cells/single_optical
+++ b/tools/test/cells/single_optical
@@ -1,7 +1,7 @@
-# Local VirtualBox-based single ONOS instance & ONOS mininet box
+# Optical use-case VirtualBox-based single ONOS instance & ONOS mininet box
 export ONOS_NIC=192.168.56.*
 export OC1=""
 export OCN=""
-export ONOS_FEATURES=webconsole,onos-api,onos-core-trivial,onos-cli,onos-openflow,onos-app-fwd,onos-app-mobility,onos-app-gui,onos-app-optical
+export ONOS_APPS="openflow,fwd,proxyarp,mobility,optical"