Merge pull request #16 from breaks/master

Added support for multiple shot types, shot types are organized in the s...
fix initial infections, allow data: urls for background images, switch to single shot for now
make users who join a round in progress automatically infected
quick fix for bullet ids, todo: config object
Added support for running behind a reverse proxy

If set also tries to bind to the port got from the PORT env variable
Merge pull request #15 from loadletter/herokurun

Added support for running behind a reverse proxy
Added optional color feature to shots and bullets, each shot can now have its own color (example usage could be to differentiate human and zombie shots)