add feature for reusable route filters

[Aras Can Akin]

When defining a route with filter, it is needed to rewrite the controller mapping each time like the following;

# routes.py
urls = {
    '/api': {
        '/post': [
            'ApiController.check_auth', # runs before me
            'UserController.me'
        ],
        '/profile': [
            'ApiController.check_auth',
            'ProfileController.get'
        ]
    }
}

In this example, check_auth is should be defined once.

[Aras Can Akin]

filters are disabled currently, decorator filters will be introduced