OpenVSwitch QoS support

implements bp qos-ovs-qos

Change-Id: Ib0e2bed8763cbca8e75ced8b2ba57c7c548ff719
Bugfixes for delete and update QoS RPC methods

Change-Id: I5c3d8c3881d26360a190246c657a81d79244ef0d
Fix double deletion of key

Change-Id: I87ef3a687b234a449e7137c153d61b9adf9b4646