Changes include:
-Replace openstack.org link with opendev.org
-Delete pylint
-Change way of adding neutron in the requirements.
-Replace common_db_mixin with 'object'. [Reference:] 957eca96f4
-Update Sphinx requirement version
Change-Id: Ie4eaa32819e04ec8c486e71430b29912e06fab29
Signed-off-by: Sara Nierodzik <sara.nierodzik@intel.com>