feat(version): add -dev flag for unversioned releases

This helps clear some confusion on the current version of Deis
users are currently working with.

[skip ci]
feat(version): add version constant

This utility package is useful for other packages such as deis/deisctl
to know what version of deis they are targeting against.

[skip ci]
fix(controller): allow unicode in config:set and app logging
Merge pull request #1806 from bacongobbler/dev-version

feat(version): use -dev flag for unversioned releases
Merge pull request #1762 from mboersma/1760-unicode-logging

fix(controller): allow unicode in config:set and app logging
ref(client): remove PyYAML dependency and save to ~/.deis/client.json
fix(client): convert client.yaml to client.json once if needed

Our use of YAML was very restricted, so a set of python string
replace calls converts it to valid JSON without requiring PyYAML.
If that succeeds, delete the old ~/.deis/client.yaml file, otherwise
ignore errors and just use ~/.deis/client.json from now on.