remove a ton of public/vendor git submodules, using CDN instead. The
reason we're removing the submodules (intead of keeping them around
for offline development) is that derby does some watchfile magic on the
public directory, and it causes a "max file limit" operating system
error (mitigated by `ulimit -u 2048`). For offline developers, you may
want to have some symlinks and a git stash handy