Move quiz entity admin page definitions to QuizUiController.
Issue #56, #51: Menu item /quiz/%/edit should be menu local task.
Add empty callback for:

- /quiz/%/questions
- /quiz/%/results
Add empty callback for:

- /quiz/%/revisions
Issue #56: Render "Create new question links".
Issue #56: Render basic layout for /quiz/%/questions.
Issue #56: Fix wrong question add link.
Merge pull request #56 from v3kwip/quiz-entity/quiz-edit-pages

Create /quiz/%/edit/questions page