Fix vim config to not crash the whole script
Fix vim config to not crash the whole script

This fixes an issue with the vim configuration part of the setup
where it would crash if the directory ~/.vim already existed and the
file ~/.vim/bin/install was not there.

professor/workstation-setup,jonsgreene/workstation-setup,jonsgreene/workstation-setup,pivotal/workstation-setup,professor/workstation-setup,pivotal/workstation-setup