Add Constraints System & GeoGroups

[yak0d3]

Addittions

• GeoConstraint: The GeoConstraint object is bound to each new geo route/group, the constraint decides the behavior of the geo-route, and sets/binds the failure callback
• GeoCallback: Made of a name, callable and arguments, this object is invokable, and is [usually] called in the Middleware handle method. All callbacks are saved as GeoCallback object inside the CallbacksRegistrar, most of the time, we don't have access to the arguments, so they are optional and can be set later via the setArguments method, which is the case inside the CallbacksHandler trait.
• CallbacksRegistrar: Responsible for the registration of all callbacks, default and custom ones, also used to bind callbacks to constraints in a way that makes us avoid route caching problems
• GeoGroup: This class can be initialized via the geogroup Router macro method, this class will behave the same way as GeoRoute, except for the part that it handles a group instead of a single route. With this, the issue #10 can be considered solved.
• The or callback, usage:

  Route::get('....')->allowFrom(...)->or(function() {
   return abort(401);
  });

  Unfortunately, this will disallow route caching, but i actually have a solution for that, and it will be implemented in the future

  Changes

• The method shouldHaveAccess of the trait DeterminesGeoAccess now accepts a boolean a third parameter instead of string, and also this method now converts all country codes to uppercase along with the current visitor's country code, this is now only handled in this method and removed from all other parts of code
• The global middleware configuration key is changed from (string) strategy to (boolean) allowed

Deletions

• The from macro was removed along with the allow and the deny methods, the same approach can be achieved with the allowFrom and the denyFrom methods

[yak0d3]

This will be split into several pull requests for ease of review. Merged PRs will be commented here.