Create a CONTRIBUTING.md file

[igorsantos07]

We should state what are the code style guidelines and whatever other rules for contributions we have (I think that, for now, only code style haha).

I think that the CS guideline we're following is: PSR-1 with braces in the same line. However, my memory is awful, so this should be investigated in the Ardent main class before commiting a CS guideline into the repository.

Inspired by #151

[dalabarge]

I'm all for PSR-1 at a minimum. However, I'd recommend that such a package follows PSR-2. If we can raise the standard for contributions then we ensure a higher quality code that is more accessible to more developers. Any chance we can take to put it a step further towards beautifully written code, the better. Entrust and other libraries will follow to some lesser extent effectively bringing up the quality of 3rd party Laravel packages with it.

[igorsantos07]

👍

[igorsantos07]

Guess this is superseeded by #268