Added box building for stand-alone phar

Since this is quite a self-contained tool, I've added phar construction using http://box-project.org/ as an option.

Feel free to toss if you're not interested (adds a bunch of dev dependencies, unless you grab the box.phar directly).

Builds to a nice compact phar with this command:

$ cd /path/to/project/
$ ./vendor/kherge/box/bin/box build