follow file path requirements for newer clojurescript compiler.

Hey,
As discussed in lynaghk/c2#49 this gets singult and thus c2 to work with newer clojurescript compilers.

I've verified that c2-demos/hello-bars works now depending on this. Also `lein cljsbuild test` succeeds.

The main source file changed to the slightly odd `singult/coffee.coffee` (to match the namespace).  For javascript distribution in unminified form perhaps it would be renamed back to `Singult.js`.