Bug #7, Database re-factor for JuxtaLearn Quiz - new DB table

* Table: "wp_juxtalearn_quiz_scaffold" - relates to Bug #1.
* Edits to model, create_table, scaffold and "wp_*" plugin PHP
Bug #7, "Finish" the Javascript scaffolding for JuxtaLearn Quiz

* Bug #1, JS to tick the right Stumbling Block/SB checkboxes per question