Replace existing PublicBodyCategories functionality with db models PublicBodyCategory and PublicBodyHeading
Use translation tables for PublicBodyCategory and PublicBodyHeading
Fix admin screen formatting issue in Chrome
Basic category admin screen
Restrict category_tag edits to empty public body categories
List categories without headings on the admin screen
Enable admins to link public body categories to headings
Set default font for admin navbar throughout site
Reinstate automatic loading of categories on get if no categories defined
Add display order to public body categories and headings
Allow deletion of public body categories with associatied bodies
Add upgrade notes for category editing feature
Merge branch 'issues/222-category-editing' into panama-develop