Revisit use of terms dashboard/courses for consistency

[taylortom]

We use the two terms synonymously, but this shouldn't be the case (for me, the term dashboard brings to mind a specific type of screen).

I propose we 'unhook' the two, and replace all references to dashboard with courses or something similar (including changing the global menu button from dashboard to courses).

This frees us up to add an actual dashboard page later.