[Pages] Create and manage static content from the UI

[netsensei]

It should be possible to create and add static pages with HTML as an administrator. This would give organisations the chance to add a bit more context about their datahub instance i.e. provide information about Copyright, Licensing, background,...

Detailed description

This is an enhancement / feature.

Context

This is important because right now, it's not possible to provide proper licensing information unless you start hacking the core code. That is: add static pages in the codebase and manipulating KnpMenu's to add those pages.

Possible implementation

• Add an overview of all pages in the admin UI.
• Add a "create/edit" form to create and edit pages.
• Add a "delete a page" form to delete pages.
• Add possibility to add pages to a menu.

Discussion

• The Datahub is NOT a content management system. We should be wary not to create a fully fledged static site with nested menu items, etc. in the Datahub. Keep it simple: only basic pages at the top level menu.
• Rethink the implementation: Maybe we just need to provide 2 or 3 blank, pre-set pages that can be enabled and edited instead? Would greatly reduce complexity, but wouldn't be as flexible.