Update README.md including module documentation

The README.md has more detailed instructions on how to include modules from Github by editing your Puppetfile and site.pp files.
Dat MIT
halp!
Update boxen-my-config for the proper login env
Refactor git handling
change $USER to ${USER} to avoid history expansion

see [here](http://stackoverflow.com/questions/15140221/weired-zsh-behavior-how-to-debug/)
script/nuke failed to delete receipts

Can't use a bare system call because we need globbing
Update README for Puppet Module sharing docs
install the version you're checking for
work with EDITOR like 'mate -w'
speed up all invocations of boxen

when running Bundler, it just so happens that --local should (but does not)
skip updating the gems in vendor/cache. explicitly skipping that update drops
most of a second off of every run of boxen.
README overhaul
allow bundler 1.x releases
Don't die if HEAD ref is not symbolic.

Examples of situations when HEAD is not symbolic:

 * You're doing interactive rebase
 * You're using git bisect
 * ... and so on.
It's cleaner to have another case: "not on any branch".
Update Puppetfile
Added Sublime Text 2
Added mongodb
Change mongodb puppet file
deleted cached puppet file