Call whoAmI on authentication to get user information

When a userContext.userId exists (ie: the user has authenticated), call
the whoAmI API to get the user’s userId (among other information). This
will be used by other API calls that are user specific.
Retrieve sections for each enrolled course

In loadCourses, retrieve each course offering’s sections before
creating the select course options list. This data will be used to
present option groups when a course offering has more than one section,
commonly for mapped courses.

The options list has not been modified to show this new information,
yet.