CS fixes

Hi spiffy,

This is just a small PSR-1/2 fixes, nothing more. I didn't expect this module to be THAT big ôÔ !

Just a few things:

- Really, can't you remove the dependency to spiffy-test ? I couldn't run the unit tests because of this. I can't see a reason why you would need this.
- There are a lot of classes that ends up with name like "ProviderInterface" instead of "IdentityProviderInterface", "SomethingProviderInterface"... I usually dont' like this as it always needs to use aliases (otherwise, ProviderInterface means nothing). I think it would be a good idea to have more explicit names.
- Note sure that AbstractGuard should extend AbstractOptions, it's not an option class https://github.com/spiffyjr/spiffy-authorize/blob/master/src/SpiffyAuthorize/Guard/AbstractGuard.php#L10