Allow $EDITOR to be set up elsewhere
Fix syntax error
Don't show a version if rbenv can't switch to it
Fixed syntax error
Fix seds treatment of tabs

Per https://github.com/holman/dotfiles/commit/3d2a856d2475f8c7e6cff6117652f92542cb6247#commitcomment-3561553.
Add `res`

`res` is a small script that facilitates switching between screen
resolutions super quickly and easily.
Update gitconfig to use osxkeychain for OSX and cache for other systems