Working CourseDAO.
Added method: Course getCourseById(String courseId).  Provides course
retrieval by course ID.
Implemented working ProfessorDAO.
Implemented untested EvaluationDAO.
Working EvaluationDAO and RegistrationDAO.
Merge pull request #2 from nathanshih/ProfessorDAO

ProfessorDAO
Merge pull request #3 from nathanshih/EvaluationDAO_RegistrationDAO

Working EvaluationDAO and RegistrationDAO
Working StudentConnectionDAO.
Merge pull request #4 from nathanshih/ConnectionDAO

Working StudentConnectionDAO.
Added examples. Fixed merged conflicts.