fixes #298 uses proper npm package for cujo.js "when"

[moricard]

The editor seems to work fine. But I have no idea if I broke something as there is no indication which version was used before. Tests seem to run fine until this error:

SockJS v0.3.1 bound to "/websockets"
Server port = 7261
Server has started.
http://localhost:7261/clientTests

events.js:72
        throw er; // Unhandled 'error' event
              ^
Error: listen EADDRINUSE
    at errnoException (net.js:901:11)
    at Server._listen2 (net.js:1039:14)
    at listen (net.js:1061:10)
    at net.js:1135:9
    at dns.js:72:18
    at process._tickCallback (node.js:415:13)
npm ERR! weird error 8
npm ERR! not ok code 0

The file used mixed tabs and spaces and since I didn't find any style guidelines, I used my default 2 spaces indentation.