unskip test_list_servers_filtered_by_ip

Bug #1170718 is fixed, so we can unskip the test_list_servers_filtered_by_ip.
Also making the test compatible with tenant+network isolation settings.

Change-Id: I31ec6baac41a084b2106bef2fb686030ba599c7f
Add unit tests for all generators

generate_json.py does not exist any longer. Using the checks there
and move them into test_negative_generators.py. From now on the checks
are usable for all generators (also valid_generator) using a base class.

In order to check for unknown types it was mandatory to change an
existing exception to a more detailed exception (TypeError).

Partially implements bp unit-tests

Change-Id: I6b5b66f8ae113c1aca471d8338334cd47ff45723
Added cleanup in some tests

Change-Id: I1b49e14c0cc2b398971922782b2f208135da2f3e
Merge "unskip test_list_servers_filtered_by_ip"
Merge "Added cleanup in some tests"
Merge "Add unit tests for all generators"
Merge branch 'master' of https://github.com/openstack/tempest