Update version of puppet-homebrew

tmux installation failed due to a dependency on libevent failing to
install correctly. The following 3 PRs are relevant

https://github.com/boxen/puppet-homebrew/pull/58 (root casue)

https://github.com/boxen/puppet-tmux/issues/2
https://github.com/boxen/puppet-tmux/issues/3
Add sourcecodepro module

Source code pro
(http://store1.adobe.com/cfusion/store/html/index.cfm?event=displayFontPackage&code=1960)
is my favourite programming font
Merge pull request #126 from alphagov/fix-tmux-installation-and-add-sourcecodepro

Add source code pro and update puppet-homebrew