* Check minimal API and docker-py versions for all docker_* tests.
* Improve docker_swarm creation/destruction for tests.
* Fail when conditions aren't met.
* Don't hardcode address for advertise_addr.
- Leave swarm at end of test to avoid breaking docker_swarm test.
- Do not update stack to avoid error leaving swarm.
- Put test back in correct group.
Felix Fontein
Matt Clay
Dario Zanzico