Corrected typo (slidshow → slideshow).
Use prefetch related to trigger polymorphic downcast.
Merge pull request #116 from nephila/feature/prefetch

Use prefetch related to trigger polymorphic downcast.
Merge pull request #112 from eliasp/slideshow-typo

Corrected typo (slidshow → slideshow).
Merge pull request #107 from timgraham/drop_django1.3

Dropped support for Django 1.3.
Added Python 3.3 compatibility.