Sometime macvim explodes and you need vim:halp

Add a `vim:halp` rake task which reinstalls vim and does some other magic.
Useful when (mac)vim starts giving "Import error" python errors or SEGFAULTs.

Also add some vim install options to the Rakefile: force lua & luajit support.
Add the netbook (local) to the known ssh hosts
Add the vim editorconfig plugin
Minor enhancements to the Brewfile
Make the install script Bash 3 compatible and update the README