clean up security groups tests

This patch clean up test codes of security groups in the
following items:
1. add a helper function create_new_security_group to replace the
   duplicate codes in test methods
2. remove duplicate test case test_security_group_create_delete
   in test_security_groups.py
3. use data_utils.rand_uuid() instead of str(uuid.uuid4())
4. import test module instead of attr

Change-Id: Iaf1a267134a12a664a0f306980c9cb39fe5ac1eb
unskip test_list_non_public_flavor

Bug #1209101 is in the 'Fix Released' status.

Change-Id: I485fb2869835497c255ef7ed2ec659120b35a910
Remove using of deprecated self.headers (part2)

Attr self.headers in rest client is deprecated now, and
should be removed from usage by service clients.

This patch removes second bunch of attrs in service clients
and from rest client itself.

part1: https://review.openstack.org/#/c/73869/

Change-Id: I109479299cd41848e78700484bed862012638c4d
Partially-implements: bp refactor-rest-client
Skip test_list_server_addresses if neutron until bug 1210483 is fixed

There is a known set of race conditions in nova when spawning instances
and setting up networking with neutron which is being addressed with
nova blueprint check-neutron-port-status, but until that's fixed in nova
we should skip the tests if you're using neutron.

Related-Bug: #1210483
Related blueprint check-neutron-port-status

Change-Id: I1661303a043b3add5eb6569f71ebccfae2b0ef68
Merge "unskip test_list_non_public_flavor"
Merge "Remove using of deprecated self.headers (part2)"
Merge "clean up security groups tests"
Merge "Skip test_list_server_addresses if neutron until bug 1210483 is fixed"
Merge branch 'master' of https://github.com/openstack/tempest