Added boxen upgrade instructions
Update firefox==1.2.0 packer==1.2.1
Updated packer to 0.6.0
Updated vagrant to 1.6.2
Added more detailed update process
Moved Upgrading instructions to FAQ
fixed spelling error
Update README.md

Other boxem fixed.
Merge pull request #587 from nbmorgan/master

Added boxen upgrade instructions
Upgrade puppet-git to 2.3.1

Closes #598
Merge branch 'master' of https://github.com/boxen/our-boxen

Conflicts:
	Puppetfile
	Puppetfile.lock
Install sublimetext package SublimePrettyJson