Remove the .git folder conditionally

Use a variable to check whether the .git folder must be removed, in
some cases projects require to keep the .git folder and therefore an
option should be present to skip this task.

@ramondelafuente for some projects we currently rely on the version given back by `git describe`. Therefore, we need the .git folder to be available in the production deployment. I don't think so many ppl will need it, so I didn't update the README, but if required, I can document the variable.

The variable defaults to true, so BC is maintained.