BUG-444: Refactored BGP-RIB configuration modules tests.

-Added tests for BGPTableTypeImplModule
-Fixed validations in RIBImplModule

Change-Id: Iaaba1f6ceb52858d6b54c0b52774dab3b39596ad
Signed-off-by: Milos Fabian <milfabia@cisco.com>
Signed-off-by: Robert Varga <rovarga@cisco.com>
Signed-off-by: Dana Kutenicsova <dkutenic@cisco.com>