Add support for release management

[fago]

Use cases:

• Create release local only and publish immediately.
• Create release and publish branch.
• Finish published release and update build:master

Commands: phapp release [VERSION] -> Creates release if necessary, finishes the release. phapp release:create [VERSION] [--no-push] -> Needs to update develop + master branches first. -> Run git:pull -> Pushes the release by default. phapp release:push VERSION phapp release:finish VERSION [--no-push] -> Needs to check whether the latest release has a build. -> Pushes into the configured origin repository -> Pushing is a separately configurable command. So we can configure WV to push two repos!!!

Extracted git commands phapp git:pull - Updates the app's main branches. Including build branches. phapp git:push - Pushes the apps' main branches in the app repository. Including build branches. Pushing should use --follow-tags. phapp git:show - List central branches and mirror repositories [Default]

phapp.yml config

• Branches that are updated and pushed.
• git_mirrors: List of mirror repositories to push into and optionally a branch regex. So build/* branches can be pushed into a separate remote if desired.

[fago]

I don't think this is necessarily something that makes sense for phapp. The needed commands probably vary a lot depending on the release workflow used, so hard-coding a certain set of commands into phapp does not make so much sense.