Some login errors I saw, fixed.

-Teachers logging in were actually supposed to go to
RegisterStudentServlet until TeachersHome gets finished
-teacher_header.jsp needed to have response instead of resp
-stylesheet needed to adjust the min-width of the container for
"username, log out" at smaller widths. May cause problems with longer
usernames
-local_db.bin contains test data that we should probably use for
demonstrating, so save it somewhere where you wont accidentally
overwrite it, or just dont commit your local_db.bin