Bug 5008 - QoS and Queue fixes for ovsdb southbound

Bug 5008 - QoS and Queue fixes for ovsdb southbound

Update the operational MD-SAL for Queue and Qos updates from the OVS
host.

Support configuration of QoS and Queue via configuration MD-SAL.

- Support for adding and deleting QoS entries.  A qos-id is used
  as a handle for qos entries in the MD-SAL.  This is added to
  the 'external-ids' of the qos entry.  Qos entries originating
  from the OVS host are assigned a qos-id of "qos://<uuid>".
- Qos entries can be assigned to a Port (termination point)
  which is present in the MD-SAL by setting the port qos
  attribute to the UUID of the relevant Qos entry.
- Qos entries are cleared from a port by updating the
  port configuration with the qos attribute removed.
- Support for adding and deleting Queue entries. a queue-id
  is used as a handle for queue entries in the MD-SAL.  This
  is added to the 'external-ids' of the queue entry.  Queue
  entries originating from the OVS host are assign a qos-id
  of "queue://<uuid>".
- Queue entries can be added or deleted to the queue list
  of a Qos entry present in the config by filling out (or
  removing from) the queue-list attribute of the qos entry.

v2 - added setting of exising qos uuid to an existing port
   - added clearing of a qos setting for a port
v3 - ovsdb.yang whitespace fixes
   - fixes for failed tests
v4 - fixed model - queue list in Qos entries needed
     a queuenumber key value
   - fixed up comments on whitespace and log messages
v5 - finished set/clear of queues list in a qos entry
   - added more description about the functionality in
     the patch set.
v6 - fixed up more whitespace, and copyright comments.
v7 - address review comments:
     - white space
     - remove unnecessary code
     - remove commented out code
     - adjust some LOG levels
     - remove unused imports

Change-Id: Idec02aaa82e1ffa66e58862ecfc5edff05050444
Signed-off-by: Eric Multanen <eric.w.multanen@intel.com>