Resource doc fixes, tiny change to fields.py

Fixes two links in resources.rst; 
Changes what looks to me to be an erroneous return value in one of the examples;

https://github.com/damycra/django-tastypie/commit/823d007abe1addf105e52b8e25ace41f6a8be5ea removes an `elif` block that looks to me like it was already dealt with in the original `if`. 


*Thanks for all the hard work*! Hope this PR is of use.