Roles alter

Changes the names of the two provided roles to "Developer" for what used to be "administrator" and "content editor" for what used to be "site editor".

The motivation behind this is to reduce the number of users assigned to the administrator role.

Special attention needs to be paid to what a user with just the "content editor" permissions can do. Can they view published and unpublished content? Can they alter menus? What other things should a content-centric role be allowed to do?

This is not ready to be merged.
Let's kill this and the navbar dependency (most devs disable overlay, this would prevent them from doing so).