Allow subnet name in lb-vip-create and lb-pool-create

Fix bug 1168998

Change-Id: I25bf357d069b99db467db43900d293f30c2a7d30
Support router-interface-add/delete by port_id

Fixes bug 1061638

Change-Id: Ie36126a38627a6707e82116fb6b7bd97755f8fd0
python3: Introduce py33 to tox.ini

Introduce py33 to tox.ini to make testing with
python3 easier.

Change-Id: Id50ca397612d4948325a0ad0f39451a16b86d5bd
Signed-off-by: Chuck Short <chuck.short@canonical.com>
Merge "Support router-interface-add/delete by port_id"
Merge "Allow subnet name in lb-vip-create and lb-pool-create"