Interface, basic tests, and fake implementation.
Implement GearClient.list().
Fix some parsing and query issues.
Simpler, faster implementation of GearClient.exists().
This edge case is no longer possible to trigger.

Moreover it would imply a significant internal bug/bad state in geard
and probably nothing would work anyway.
Use list for functional tests, and add functional tests for listing everything.
Return client from `start_container()`.
Make the test more lenient.
Better docstring.
Make pyflakes happy.
Make flake8 happy.
Resolved merge conflicts
Satisfy flake8
Remove useless blank line
Link to a Github issue
Merge pull request #153 from ClusterHQ/list-containers-32

List containers managed by gear (fixes 32)