Bump required docker-py version to 0.5.0.

This version doesn't have a bogus dependency on coverage.
some failing tests
end of day commit, work in progress
more tests and implementation of to_flocker_yaml
Merge branch 'master' of github.com:ClusterHQ/flocker into fig-flocker-changestate-yaml-796

Conflicts:
	flocker/node/_config.py
re-factored Fig-to-Flocker-YAML converter as generic converter
Merge remote-tracking branch 'origin' into fig-flocker-changestate-yaml-796
fix line missing test coverage
addresses review comments
use different internal/external port numbers in test
Merge pull request #845 from ClusterHQ/fig-flocker-changestate-yaml-796

Fig flocker changestate yaml 796
Merge pull request #859 from ClusterHQ/bump-docker-py-version

Bump required docker-py version to 0.5.0.

Author: @tomprince 
Reviewer: @wallrj
Merge remote-tracking branch 'origin/master' into pre-release-rpm-versions-662