Scale.module needs more love

- [x] Rename scale -> quizz_scale
- [x] {quiz_scale_node_properties} -> {quiz_scale_properties}
- [x] {quiz_scale_properties}.nid => {quiz_scale_properties}.qid
- [x] {quiz_scale_user_answers}.question_nid -> {quiz_scale_user_answers}.question_qid
- [x] Add more columns for {quiz_scale_collections}: name, label, uid, data, module, status
- [x] Provide entity api for scale collection
- [x] Move logics to collection's controller
- [x] Drop {quiz_scale_user} table.
- [x] Convert global configuration for questions to question type entity.
- [x] Update test cases
- [x] Make use of new entity API in quizz_scale_install()