Merge pull request #132 from joshmoore/delete-tags

Add delete-tag
Merge pull request #133 from sbesson/unrebased_prs_multibranch

Refactor unrebased prs command
Add `set-labels` from sbesson

See: https://gist.github.com/sbesson/8362686
Include repo logging and activate
Fix flake8 errors
merge master -D org -I include -E exclude: PR 135 (Add `set-labels` from sbesson)