Add executors to bind a command to a consumer

There's a very close relationship between the command and its consumer: other command arguments could mean a different consume strategy.
At the moment I have to change the value passed to the GitStatusConsumer, which means I have to search for all places where this consumer is used. With a GitStatusExecutor I would only have one spot to fix it.
If there are other projects which are using these classes by implementation, we could have a problem.