Remove the get_service_id method and inline python

Keystone client's endpoint-list now returns the service id associated
with each endpoint.

Fixes Bug# 1223534

Change-Id: I2ff56803f5f9d1f57a8fc1eabaf5ac5b13310b6d
(cherry picked from commit 64112f5eb1695de3cc5b12de197043ca99768818)