fix a typo in the help message of quantum_controller_addr

Signed-off-by: YAMAMOTO Takashi <yamamoto@valinux.co.jp>
move openstack.common into the contrib directory

adjust import order in ryu-manager and add a comment.

Signed-off-by: YAMAMOTO Takashi <yamamoto@valinux.co.jp>
fix a typo in a comment

Signed-off-by: YAMAMOTO Takashi <yamamoto@valinux.co.jp>