Share limits between several routes

[g-p-g]

It looks like the current implementation does not allow sharing a single custom rate limit among several routes (global limits excluded).

For instance, take the example where you have a /slow route limited to 1 request per day. What if I have a second route which I would like to share the limit of 1 request per day along the other /slow route? Right now the code will limit each route to 1 req per day, while it would be useful to allow 1 req per day for all the slow routes combined.

[g-p-g]

Closing in favour of issue #8