Update dependencies: clojurescript, ring, compojure, cljsbuild, environ
Make development mode work again, load react from jar

To run with figwheel, we need to disable cljs optimizations. This also
means that we manually need to require our main namespace. Before we had
that code in index.html, but in production we only need to load app.js.

Since we already inject JS for the browser repl, we can expand that to
also inject the necessary includes. I've also added a compojure route to
serve up react from the com.facebook/react gem, so we can serve it
ourselves instead of relying on facebook's CDN.
Switch to Weasel, and other improvements

Switched from Austin to Weasel for a browser-connected REPL. I regularly
got issues with Austin that after a while the REPL became
unresponsive. Hopefully this fixes that. Weasel seems to bring some
other niceties as well.

Did some testing with a project name containing a dash and found some
places where {{name}} had to be {{sanitized}} or vice versa. Switched
the uberjar name to not be sanitized, this is more in lein with the jar
naming leiningen uses by default.

Finally the "is-dev" thing on the clojurescript side now actually
works. The idea is that in dev mode we set an "is-dev" class on the
<body>, so the clojurescript side can know we're runing in dev mode and
needs to connect to the REPL and Figwheel. So in production no
REPL/figwheel connections will be started.