Allow overriding abstract type Sentry is bound to in service container.

[hackel]

This is a fix for #24. I used a public static property so that you can also do this:

class SentryFacade extends Facade
{
    protected static function getFacadeAccessor()
    {
        return SentryLaravelServiceProvider::$abstract;
    }
}

[dcramer]

@hackel I'm going to merge this in, but what are your thoughts on making the default Facade be this type but titlecase?

[hackel]

@dcramer I think that makes sense. I tried to change as little as possible to make it work. I don't generally use facades myself. We could create the facade alias manually:

if ($this->app['config']->get('auto_create_alias', true)) {
    \Illuminate\Foundation\AliasLoader::getInstance()->alias(studly_case(static::$abstract), SentryFacade::class);
}