Extend user rolls to control admin menus and what user is allowed to do in the admin interface

Ghost has several different user rolls. However, it would be reat to be able to limit what the user can see or do in the admin interface.

This mostly focuses around an author or contributor.

It would be great to have an interface to extend or limit the roll abilities in the backend. For example, I do not want a contributor to add videos using the editor, or add/edit the custom meta tags for twitter, facebook etc.

If I am an author, I do not want the author to manage tags as an example.

Then, when adding content, we would like to restrict what these rolls are allowed to add to content.

I hope this is clear, and I beleive would be a great addition to the system.