Add a README

Add GPLv3 License

Add `git-branch-validator` - a `git-flow-avh` git hook

`git-branch-validator` checks that working branches (`bugfix/*`
`feature/*` `support/*` `hotfix/*`) are prefixed with a JIRA ticket
ID.

If the branch is a release branch, it checks that it is named in
way that somewhat resembles a version number.