Boss executable

Yesterday while writing a [Homebrew](http://mxcl.github.io/homebrew/) formula for Chicago Boss that would install CB into /usr/local, I realized there was no real "boss" command that could be run easily from anywhere to create a new app or manage the app in the current working directory. So I wrote one.

This commit allows devs to do things like "boss new APP" or "boss start", just like one would do with the "rails" command. Because the boss command follows symlinks, it works well both as bin/boss when being run from the ChicagoBoss directory (instead of using "make app project=FOO") or as simply boss in the context of an installation on the user's path.