Sort Content Items

Content Items are not being sorted from the SQL Layer through the API. Therefore, the main content items from each exhibit are different between test.chronozoomproject.org and www.chronozoomproject.org.

The fix is to add an ORDER BY clause to arrange by [order] field.

As a side effect: Fixes #309 and Fixes #309.

Code Review (Approved): http://mrccodereview.cloudapp.net/ui#review:id=1159