The big Post model refactor is done...ish.

Author's model needed a minor change.  __str__ is Python 3, we're using Python 2,
so I changed that to __unicode__.  Also gave it a get_absolute_url() function for
super convenience.

Author's and Post's views have been updated to package and parse the updated Post model data.

Post's admin has registered every new model defined.

Post's model has been brought in line with the spec.
- NEW: guid, title, description, origin
- MODIFIED: privacy -> visibility, format -> contentType, date_created -> pubDate, date_modified -> modifiedDate

Post-related templates have been revamped to not only support the new Post model, but also
conform to Bootstrap's conventions.

And now for some (hopefully) GitHub black sorcery...
Fixed #39
Fixed #34
closed #28
Closed #26