Adding checks to the alerts for student training.

Fix for ORA-728 and ORA-729 - Alert messages when there are no training examples and alerts when student training is disabled.

Now checking both scenarios before display an alert. Added tests accordingly. 

@wedaly @gradyward 
I liked this change because the "student_training" module is checked in a few places in the template, and as it stands, our fixture renders as if it were disabled with a number of hidden elements.