Retrieve the list of availability zones from nova in Fn::GetAZs

Fixes: bug #1096001
Change-Id: Ie5c46ae038dff4f53ba8d722e878583044bd194c
heat tests : run_tests.sh reinstate text coverage report

testr migration removed the text CLI summary report, so add
it back in now for easy visibility of coverage results

Change-Id: I419b1a9ea45f391a2cf623ad4431c93982ae5231