Remove `Ownable` from `Relationship` model
Add role-editing to Person list on admin page

* Adds `__sort` and `__sort_desc` parameters to resource endpoints
* Removes Authorizations widget
* Adds `user_roles` to `Person` resource representation
Pin `requests` module to 2.0.0 for now

* Bugfix in requests==2.0.1 breaks all tests due to cookie persistence
  (https://github.com/kennethreitz/requests/issues/1630)
Merge pull request #508 from reciprocity/feature/pin-requests-version

Pin `requests` module to 2.0.0 for now
Merge pull request #509 from reciprocity/feature/people-authorizations

On admin page, add role-editing to People widget; remove Authorizations widget
Merge pull request #507 from reciprocity/feature/myview

My Work (LHN enhancement and My View/Profile pages)
Merge branch 'develop' into feature/myview_audit