Include local gitconfig at the end of .gitconfig

Allows for customizing git's commit message template and overriding fetch.prune.
Prevent evil nbsp from being invisible

Not seeing these can be problematic, since you won't know what broke your code on the day that one of them sneaks in.

Here's a few other common characters people use for this: https://github.com/search?utf8=%E2%9C%93&q=nbsp%3A+extension%3A.vimrc&type=Code&ref=searchresults
Updating readme to use thoughtbot/formulae

Brew bundle is deprecated. fixes #309
Removes Brewfile, no longer needed
Ignore tags file, but not directories named tags
Wrap at 72 characters for git commit messages

The body of a git commit message is conventionally ([1], [2]) wrapped at
72 characters. This commit adjusts .vimrc to automatically wrap the body
of git commit messages at 72 characters.

[1]: http://robots.thoughtbot.com/5-useful-tips-for-a-better-commit-message
[2]: http://tbaggery.com/2008/04/19/a-note-about-git-commit-messages.html
Add /usr/local/sbin to PATH

Some homebrew formulae, (e.g. [RabbitMQ][1]) link binaries here.

[1]: https://github.com/Homebrew/homebrew/blob/master/Library/Formula/rabbitmq.rb