Fixing challenge complete dialog

This fixes #181 and #123 

I moved the MapRoulette JSX file to a separate directory /jsx in the MapRoulette root, notes on this:

I installed the react-tools node module, so I can precompile the JSX into javascript for debugging while I am working on it, using

[17:06:08] $ jsx --watch jsx/ maproulette/static/js/

This only seems to work though when the source file (in the first directory) has a .js extension (not jsx). (Is this a bug? Am I doing something wrong?) Which is why I moved the jsx file into a separate directory in the maproulette root in my branch fix_challengefinished, which contains some work on correctly showing the 'challenge is done' dialog in various situations. This work is now tested and done, so I plan to merge it into master, but let's discuss what the best workflow is for the jsx, and the best place for the jsx files.