Add checks to make sure Vim, Git, and Curl are all installed.

Create backups of existing ~/.dotfiles and ~/.oh-my-zsh

Quote all FS paths to ensure people with weird paths don't fuck up the
script.
Use single brackets for SH support.
Remove "set -e" it causes errors when calling the oh-my-zsh script and
exits because "source" isn't built into SH.

Remove manual bundle install, spf13 install script calls it for us now.
Merge pull request #3 from larzconwell/master

Safe install scripts are cool!