Teach Form::create() to accept a map of field and list of role id

This will be used to omit field inputs to be rendered in forms
Protect role_id from edit for non Admin users

Closes #434
Refactor NodesController::search to use Search plugin

- Fixes additional hardcoded model aliases
- Get rid of legacy search code
- Fixes #291 and #161 as a bonus
Merge branch '2.0-field-access' into 2.0