Map Casting Craziness

[ilanpillemer]

SignedRequestMap provides an interface to different forms of the Map to handle casting craziness between different environments. (eg Websockets and JAX-RS).

However the client still needs to somehow know what to choose requiring assumed experience with the craziness. This should be improved to use some kind of creational pattern (factory perhaps) so the client just gets the right kind of Map and doesn't need to even know that there is craziness.

Also this moves all the specific knowledge code into the signed library, and future changes would probably not have changes also in clients, and be localised to the library and thus transparent to clients.