Lot of work on Add Class

Added an app icon for us. Also did a lot of work on the add class
activity. Still trying to get the layout fine-tuned. I think I need to
make sure the weight of each TableRow element is the same, and
proportionally size out the views within to make the label TextView the
same percentage of each TableRow. Also went ahead and instantiated a
variable in the .java file for each of the Views.