Submodule updates

* syntastic
* vim-eunuch
* vim-rails
* vim-rbenv
* vimux
* heroku-fork
* heroku-remote
* heroku-surrogate
* heroku-wildcards
Test run of new submodule-update.rb script

script now creates a decent commit message and commits after running the
update - still should port the update itself to ruby instead of this
lame %x() business

(picked up a vim-rails update this time)
add auto-commit here too