Vim: make require JS snippet convert dashes like underscores

This snippet converts snake_case to CamelCase, but I also want to
convert dashed-case in the same way.
Update submodules
Teach update script to update prezto submodules

After updating my submodules today, there were some dangling nested
submodules that were missed in the .zprezto directory. This commit
prevents this from happening again.