Improve creating a new profile in admin

[Dries Desmet]

Since the profile model is related to Django's user model, you have to create a user first and give the user a name and password if you want to create a new profile. A password is irrelevant for users in the group 'lesgevers' and so should be auto-generated. In the admin, the change/edit page for profile should show an adjusted form that incorporates username and other 'user' fields that are relevant.

[Dries Desmet]

Issue #6 was marked as a duplicate of this issue.

[Dries Desmet]

When testing yesterday, the procedure is fine as it is now. You simply have to remember that to add a 'begeleider' for example, the procedure is as follows:

1) Go to admin 2) Go to 'Add user' 3) Fill in a username (which is a unique name that counts as an id, can't have spaces in it) 4) choose a password (have to fill this in, but is never used, don't need to remember it either) 5) Hit Save 6) You'll get to a detail page where you have to: - Fill in the First Name and Family Name - Assign the group 'begeleiders'

A profile is automatically added, which means that a new 'begeleider' will show up in the 'team' page.

[Dries Desmet]

The functionality as it is now is sufficient.