Extracting get group roles for project logic to drivers.

get_group_project_roles is now implemented in each driver.

SQL and LDAP backends will see significant improvements on
performance (less queries made to resolve the groups).

KVS backend now supports inheritance and runs correct unit
tests.

Co-Authored-By: Pablo Fernando Cargnelutti <pablo.fernando.cargnelutti@intel.com>
Change-Id: I7a0190cd4a3b1eb26a09ef6436ca5450cf837135
Closes-Bug: #1205506
Merge "Extracting get group roles for project logic to drivers."