REST connector changes and fixes
* Currently `updateAttributes` does a PUT request, but it is actually
  formed as a PATCH request, which breaks on my DB. Override
  `updateAttributes` logic to support both
* Add `getModel` helper to `RestConnector`, to play nice with `updateAttributes`
* Fix various places where `idName` wasn't used
* Add `patch` method to `RestResource` to perform PATCH operations
* Add custom filter support for our app, will refactor this out for a PR