Config file generator

[veewee]

After installing grumphp with composer, there needs to be a check if a grumphp.yml file exists.
If it does not exist an extra command needs to be executed. This command will load default values from composer.json and will try to guess the git path.
The resulting file will be placed in the composer directory.
This command will run before the git hook is added. This way, we can always be sure that the config file is pointing to the correct locations.

[veewee]

Fixed in v0.1.3