[Permissions] Add a permission to view the settings page of a course

[PaulvanEmden]

Problem statement:

In some cases you want to limit users (teachers) to make changes to course settings, but they always have access to this settings page.

Proposed solution:

Create a permission which enables you to allow course roles to access the course settings page or prevent them from having access to it.

User role(s):

instructor,ta,designer,observer