ring-server dependency is not picked up by leinjacker

Because dependency names are expanded in leinjacker, when testing to see if the ring-server dependency is already present, it fails, thus preventing adding exclusions for ring-server if necessary (for example, if testing ring 1.2.0-beta2).

(https://github.com/sattvik/leinjacker/blob/master/src/leinjacker/deps.clj#L41)

I'm not sure this is the best way to handle this--it may make more sense to do a pull request for leinjacker, making dependency matching more robust--but this works and is pretty minimal.