Add first pass at Ember guidelines

These are the first few things I've seen that are consistently useful. All feedback and input is appreciated.

cc: @jsteiner @BlakeWilliams @seanpdoyle @halogenandtoast @creuter @MattMSumner @JoelQ 
@JoelQ you are killing me today. If you recommend one more thing that I had originally I may cry. :smile: