Fixed a couple of runtime issues due to the existing support for the legacy vs MD...

Fixed a couple of runtime issues due to the existing support for the legacy vs MD-SAL based openflow plugin.

1. In addition to filtering out the openflowplugin bundles, also filter out the extension bundles.
2. Bringing the visibility of legacy vs MD-SAL based OpenFlowPlugin to Java Runtime.
   The [-of10|-of13] flag is currently a script-only flag & is lost at the runtime.
   During Hydrogen time-frame, ovsdb project also added another redundant runtime flag ovsdb.of.version
   to determine the SAL to choose. AD-SAL vs MD-SAL. Currently ovsdb is the only project that uses both
   this flag and also the legacy plugin. Hence added a simple -Dovsdb.of.version based on [-of13|-of10] flag.

Signed-off-by: Madhu Venugopal <mavenugo@gmail.com>