Revert "Remove supertab"

This reverts commit 560bccc060d70e82d1fa4789a1c62439271f4e65.
Adds dockerfile syntax and vim snippets
Remove autofold because performance is not great
Use envvars for Git
Docker + Vagrant and a few misc tweaks
Removing email from gitconfig
Transparent MacVim is not so rad anymore
Loading from correct global gem
Relative line numbers is terrible for pairing
Setting fold level to something crazy
Use GHE URL
Change AutoPairsShortcutToggle