Add FeinCMS and basic ContentTypes. 

Merge after #3
Two things here:
  * FeinCMS comes with some template tags that we use in the current proof-of-concept code. 
  * I personally try out new things outside mozilla's playdoh limits, to see how are working, the progress django has made, etc.

These said I don't have a strong preference so if you want to keep jingo/jinja by all means. We will have to re-implement feincms tags (or more specifically the tags we need) which is maybe out of the scope of this pull request.