`correct_all` considered harmful

After enough times dealing with arguments to commands, I looked into how
to selectively spell check in zsh. `correct` is better than
`correct_all` because it will ignore arguments while still correcting
the commands themselves (which is more what I get wrong).
Alias 'be' to 'bundle exec'
rvm--, rbenv++
Swap be alias for bundle-exec.sh
Add rollback alias
Switch prefix from C-a to C-o--Michael makes a good point
Save last run test command and run it when not in a spec file