improved typescript typing and organization of uproxy-pc 

* fixes a bunch `any` typings (but not all of them)
* moves the .d.ts file to live with it's definition (style-fix)
* renamed `freedom-interfaces` directory to `freedom-declarations` to avoid confusion with freedom interfaces in core providers, and to be more specific. 

TESTED: 
* grunt test
* manual test of `samples/freedomchat` (load chrome extension, then sending messages back and forth between the test inputs and looking at the console log). 
* manual test of `samples/chat`
* manual test of `samples/chat2`
But isn't the return type of the callback irrelevant to `UproxyPeerConnection`? What if you're chaining together callbacks and need to return something to the next? It seems like a great use of `any` to me.

Anyway, it doesn't make much difference here.