[TESTS] Low test covarage for Endpoints handler

[Maysa de Macedo Souza]

The testing coverage for the EndpointsHandler[1] is below the ideal. New unit tests[2] need to be created to cover possible scenarios.

The following scenarios could be added:

- on_present method: check the event is skipped (meaning no crd_spec is created or updated) when the Endpoint has no Pods defined or it's a headless Service.
- on_present method: check the event is skipped (meaning no attempt to updated crd) when the Endpoints has annotations defined, as the
Endpoints annotations are going to be converted to CRD.

[1] https://github.com/openstack/kuryr-kubernetes/blob/master/kuryr_kubernetes/controller/handlers/lbaas.py
[2] https://github.com/openstack/kuryr-kubernetes/blob/master/kuryr_kubernetes/tests/unit/controller/handlers/test_lbaas.py

Example of Endpoints with annotation http://paste.openstack.org/show/799270/