Merge pull request #66 from powerist/working

Hardcode each VM's tenant id as 1, if tenant_info is None
Merge pull request #67 from powerist/working

Add timeout to gateway flow
Fix bug and code cleanup

(1) Bug: InceptionRpc/InceptionArp/dcenter_to_rpc circular
dependencies

(2) Code cleanup: remove unncessary Inception.single_dcenter and many
occurances of CONF.peer_dcenters
Merge pull request #68 from changbl/working

Fix bug and code cleanup
Modularize switch connection