Previously fucntional tests for network segment feature are skipped
as neutron 'segment' API extension was disabled in the gate.
We now enable neutron 'segment' API extension, so we can safely drop
the check for the segment extension from the test code.
Also setup code in test_network_segment is moved from setUpClass to
setUp. There is no good reason to do them in setUpClass and
having them in setUp simplifies the test code.
no user once this commit is applied.
Change-Id: I183310b94d9b6d7f4311a3859b59dc22d36440db
198a486413