Added two custom Button classes inheriting from dijit/form/Button. These automatically set CSS classes to properly style these buttons. Both classes take an iconType property (to set icon, null if no icon) and highlightColor property (to set the base/highlight color for the button).
-Proper styling for these classes and the rest of the mockup depends on the dijit/themes/gamelab folder and dijit/icons folder. These are marked as external references, so cannot be committed at this time.
