Fix ssh connect method for scenario tests

We should try to connect via floating, not fixed network.
Configure tempest for testing heat stacks

Our heat image requires more memory to boot properly, so
add a special heat flavor for the image. Also try to
autodiscover the image and add it to the tempest.conf
Forcefully enable v3 api tests

They are disabled for icehouse by default, but since we
enable v3, we probably should test it as well.
Merge pull request #96 from dirkmueller/nova_v3

Forcefully enable v3 api tests
Merge pull request #93 from dirkmueller/ssh_connect

Fix ssh connect method for scenario tests
Merge pull request #94 from dirkmueller/heat_tempest

Configure tempest for testing heat stacks
Enable also the lbaas_scheduler extension when LBaaS is available
Merge pull request #97 from dirkmueller/more_tests

Enable also the lbaas_scheduler extension when LBaaS is available