Push stacktira scenario to icehouse

This patch moves stacktira to the icehouse release
and contains a couple of other minor fixes for the
stacktira scenario:

the default mirror has changed due to stability issues

services are being gradually moved to bind only to the
internal interface, and haproxy will forward traffic

notifications support has been added

the firewall on the internal interface between control
and compute has been opened to allow all traffic for VMs

Accommodate some changes in openstacklib structure

Add ML2 support.

Change-Id: I23fb8048f0e0463d8c16998b5bfa8c797a295445