Updates setup.py - corrects name of requirement

python-dateutil instead of python_dateutil
Fixes #884. Authorization for update should be only called once with a fully hydrated bundle
Fixes #850. Instead of using path to determin if we are dehydrating a list of resources or a single resource, we explicitly pass a boolean. This should also make writing tests easier as we no longer need to have path defined for requests.
Merge pull request #913 from ClearcodeHQ/master

Fixes requirement name
Only save related models if they've changed; closes #397, #594 and others.

Extra tests assuring through model metadata is saved; fixing backwards/forwards incompatability with MockRequest