Handle form groups in form editor

Summary:
- Add form group views and move attribute lists under those
- Ability to add / edit / delete form groups
- Handle dragging from one list to another
- Update to stable jquery.ui
- Move group list views creation into FormEditor.render - Fixes T811

Limitations:
- Can't reorder form groups yet

Test Plan:
Run `grunt build:css` for styles first
- Go to manage forms -> edit a form
- Add a group
- Edit a group
- Remove a group
- Drag fields between groups
- Reorder fields
- Add new fields to groups

Reviewers: aMoniker, shadowhand

Reviewed By: shadowhand

Maniphest Tasks: T811, T681

Differential Revision: https://phabricator.ushahidi.com/D342