BUG-1287: migrate bgp-rib

-fixed config tests

Data store has a new set of APIs, which are more efficient. This is a
straightforward migration, without taking advantage of the full APIs
available.

Change-Id: I3c205fecc08d6ef7f8bedfd481a77a1aeafab7d6
Signed-off-by: Robert Varga <rovarga@cisco.com>
Signed-off-by: Milos Fabian <milfabia@cisco.com>