Create CONVENTIONS.md

First draft of a document to assist new cookbook developers.
control modifier key required to add to sidebar
Improves customization of dock preferences

- namespaces preferences under 'sprout'
- adjusts multi-word attribute names to use underscores
- makes more of the attributes optional
- comments out some attributes to allow more of the default settings to be used.  But I left the comments in so that people would have a better idea of what could be done.
Merge pull request #196 from codeword/dockPreferences

Improves customization of dock preferences
qt works without --HEAD on Mavericks now
(it actually doesn't work with --HEAD anymore)
Merge pull request #200 from hungryzi/qt

qt works without --HEAD on Mavericks now
Merge pull request #192 from mikem/fix-home-dir-in-sidebar

Fix adding home dir to Finder sidebar