Fix Issue #765 : Successfully Import with Django 1.6

This patch fixes tastypie's failure, in Django 1.6, to import certain resources that have been moved around form prior versions of Django.  It resolves issue #765.

As far as I can tell, this patch complies with the contribution guidelines in that:

1. It is clear
2. It works across all supported versions of Python/Django
3. Follows the existing style
4. No comments needed
5. Causes existing tests to pass because tastypie otherwise cannot be imported by Django 1.6
6. Does not change a public API.
7. I am the original author, and contribute the patch under the BSD license.
8. Adds me to the Authors file.