Fix QoS information in initialize_connection() result

Currently the entire QoS information (if any) is included in the result of
initialize_connection() even if the consumer of the QoS is 'back-end'. Also
the format for QoS specs also is changed so that front-end (Nova) can
parse correctly. Add unit test to cover initialize_connection().

Closes-bug: 1259957

DocImpact

Change-Id: Ibc5e92cc1ddf6404e5b234ef524698feae282eec