 * Fix mimetype handling which seems to have been really quite broken
   for god knows how long. It now all behaves as you'd expect.

 * Abstract out template_loader option, which should be a callable
   which takes a (template_name, data_dict) and returns a string.
   The default is the existing Tempita stuff. This interface will
   probably change. It can be an object configured however it likes,
   currently that's just handled in the paste.deploy factory.

 * Internal refactoring of components for easier pluggability of
   custom edit apps (which handle editform, addform and save) and
   view apps (which handle rendering)

   Demo of custom view apps: custom display for text/csv+hbmp format!
