Hooks refactor

[alessandro-fazzi]

Problem and solution were analysed in #532

One more important feature is added here: hooks can be configured to not raise exception if their command fails. This is crucial when you have a deploy chain where some commands may fail (maybe due to external services? or just because they are not important?) and you want your deploy to continue.
The error is visibly logged by the way.

This is an example of a working new hooks structure inside movefile.yml

  hooks:
    push:
    pull:
      before:
        - command: 'exit 1'
          where: local
          raise: false
      after:
        - command: 'exit 1'
          where: remote

Hooks are always executed in order and are synchronous, so the configuration should be procedurally fully respected.

The initial goal is accomplished, since we can order before and after hooks with any regard to the environment where they'll be executed.

[alessandro-fazzi]

Documentation will be updated after the merge and before the release