Implement simple deletion to answer button custom element
Add default category, category validations, and question body to routes

A default category is seeded, but is dependent on the front-end for
defaulting all newly created questions to be included in this category.

Categories now need to have a category name as a bare minimum - an
nameless category is quite useless.

The question routes now include the posting and putting of a question
body q_body.
Disable editor panel with overlay when question not being edited
(commented out)

Feature currently commented out to ease development of answer editing
behaviour.
Fix bug in answer deletion route
Implement frontend-backend answer deletion and editing

Selection of correct answers for MCQ and true-false questions has yet to
be implemented though, but simple editing of answer text is enabled.