Fix error while attempting to view nonexistant program
Handle validation errors while creating programs
Refactor program validation
Update student creator to handle validation errors
Update student form to handle validation errors
Refactor validation error messages in JSP

Move the JSP code to display validation errors into a seperate,
reusable tag.
Update Student Enroller's enroll student method

Make StudentEnroller#enrollStudent handle invalid input. E.g. blank
and nonexistant student and program IDs.
Make Student Enroller's List Unenrolled Students more robust

Update StudentEnroller#listUnenrolledStudents handle invalid and
nonexistant program IDs without throwing exceptions.
Remove broken back button on main layout
Make title on main layout go to home page
Fix Logout button on main layout
Remove broken links on treasury page

Removes the view by Student and Instructor buttons from the Treasury
page. We can re-add these after the features are actually
implemented.
Fix broken link on program treasury page
Remove broken link on students page
Tweak layout on enroll student page
Merge pull request #28 from fantastic-five/fixes

Fix various errors and inconsistencies