one compilation error to be solved by making http generics too

@cvasilak here is a PR (not to be merged but to discuss the point you raise on generics)

- problem with generics is that when you use them, you nee to spread to all others classes...
For example here i introduce Generics in class description and protocol. I make a common protocol ResponseSerializer which is implemented by 2 classes JsonRequestSerialiser (which implement the type to AnyObject) and JsonSZResponseeSerializer (this one is Generics)
==> problem is how to integrate it with Http? 
should we make Http generic too ? like i did... although i still get a compil error

TODO:
- not sure i like URLMatcher, i'd put Generics, in MasterViewController:
        self.http = Http(baseURL: "http://igtests-cvasilak.rhcloud.com/", responseSerializer: JsonSZResponseSerializer<Developer>)
- fix the error

Let's sync tomorrow