Added support for QML to Weasel

Qt 5.3 added a QtWebsockets module which makes Weasel the perfect candidate for a QML/JS Clojurescript repl.

I added a weasel.repl.qml namespace which tries to mirror weasel.repl as much as possible.

I also added a trivial weasel.impls.print ns to so that the same repl server can set the print function regardless of whether it's a regular Websocket, QML or possibly say a Node.js repl.

I posted details here about how I actually got a REPL working in QML: https://groups.google.com/forum/#!topic/clojurescript/bSBfH1hazSg
Yes, could we add a `debug` level? There are times especially with QML that it's useful to see this output. Many times I found QML throwing exceptions and then had to look into these messages to see what the problem was - that's partially how I figured out what tweaks were needed for the QML environment - not easy!

Would it be possible to have the log level as an atom somewhere? There may be cases where one wants to enable the `debug` level during an active session.