Fix Vim exit code

I was getting an exit code of 1 when exiting Vim. Setting the filetype
to on before setting it to off fixes this. See
http://unix.stackexchange.com/questions/14497/why-would-vim-return-non-zero-exit-code-if-i-exit-immediately-after-opening
Reconfigure chruby

I also set a default ruby version in .ruby-version.