Not for merging: Add a link to run a script.

Hopefully there are better ways to just run some coffescript test code while
having access to the Galaxy-Zoo code.
Not for merging: Add  MurraycTreeExporter to get XML for questions.

And use it in the hacky murrayctest hook that I added in the previous
commit. I still hope there is some easier way to just run this code
while having access to the other code.