Update Brewfile with various library installs

- ctags (http://ctags.sourceforge.net)
- git-extras (https://github.com/visionmedia/git-extras)
- hub (http://hub.github.com)
- jq (http://stedolan.github.io/jq/)
- spark (http://zachholman.com/spark/)
- tmux (http://tmux.sourceforge.net/)

Issue: #26