Changed type signature of JSON.fromString; added multiplayer mario example

core_js:
re-ordered cat.sh, and added the Signal/WebSocket.js
changed implementation of JSON.fromString

elm:
changed type hint of JSON.fromString

Examples:
added client and server code for Multiplayer Mario!
server code is written in golang, source https://gist.github.com/1316852 with (very minor) modifications