Initial commit to support Janus plugin for Quantum in stack.sh
   - Keep Q_PLUGIN=ryu
   - Add 'janus' to ENABLED_SERVICES list
Modified stack.sh to support Janus plugin for agent nodes as well
   - Now use Q_PLUGIN=janus
Added support for fv-agent
   - Updated ctrl-localrc and agent-localrc's to include fv-agt
   - Updated stack.sh script to start fv-agt if enabled
        - Must add "fv-agt" to ENABLED_SERVICES list
Fixed bug in lib/janus file for setting sql connection address
Merge branch 'silver' of https://github.com/t-lin/devstack into silver
Merge pull request #20 from t-lin/silver

Support for Janus plugin in Quantum as well as FV-Agent