Fixes #312

Somehow this pull request ended up in the develop branch. Sorry about that. Let me know if I need to do it again. I'm not completely satisfied with this fix. It might be necessary to alter the versioning.py logic so that there is a distinct update function called for PATCHes to reflect they fact that they are partial updates and may not affect version number depending on which fields are updated and if partial versioning is being used. Whereas POST and PUTs will always create a new version because they are document-complete updates.