Merge pull request #135 from joshmoore/set-labels

Add `set-labels` from sbesson
Use tmpdir fixture for deploy unit tests
Use tmpdir to clone snoopy sandbox
Add submodule recursivity to scc check-milestone command

- Move main logic to standalone check_milestone() method
Add logic to build tag from release using get_tag_prefix()
Refactor PR milestone check/set and add permissions check
Add permissions check to scc check-labels
Rename scc unrebased-prs command as scc check-prs

- Rename corresponding unit/integration tests
- Fix command order in scc/main.py
merge master -D org -I include -E exclude: PR 136 (Use more pytest fixtures)
merge master -D org -I include -E exclude: PR 137 (Admin tools)