added few error messages to Add Category
Merge branch 'master' of https://github.com/jjfazio/308Grader
added few error messages to Add Category and Default Catrgory is Total
Merge branch 'master' of https://github.com/jjfazio/308Grader
Category is done. Error checking works
Merge remote-tracking branch 'origin/master'

Conflicts:
	trunk/implementation/model/assignments_categories/Category.java
Category merject Only needs tests
Merge branch 'master' of https://github.com/jjfazio/308Grader