Setup script for the git hooks in .git/hooks/

[guillaumeaubert]

Setting the hooks involves:

• creating all the hooks files;
• making sure the Perl interpreter points to the right location;
• making the hooks executable.

It's easy to miss a step or incorrectly perform a step, so it would be nice to have a githooks command with the following interface:

• githooks --install or githooks -i: set up the git hooks required for App::GitHooks to work in the current repository.
• githooks --uninstall or githooks -u: remove the git hooks previously set up. This should be done safely, i.e. with a verification that we're not removing a non-App::GitHooks hook.
• githooks --version or githooks -v: print the current version of App::GitHooks.
• githooks --list or githooks -l: list all the plugins currently installed in the system. It would be nice to have a list that distinguishes between the active and inactive plugins, in case there is a .githooksrc file that restricts what plugin should be run.
• githooks without arguments: print the usage information.

Thanks to @jacobmaurer - one of our conversations about App::GitHooks triggered this idea.

[guillaumeaubert]

Implemented, except for githooks list which is a nice to have but will require some refactoring of App::GitHooks->get_plugins to make some of the internals of that subroutine publicly accessible. I've opened GH-8 to follow up on that feature.

Another implementation note: I went for the perlbrew/git style of having a command as first argument, i.e. githooks install instead of githooks --install. Further arguments are supported via the standard --, just like perlbrew/git do.