Big Push: First/Last Name Split

Added first_name and last_name columns to DB for students, instructors,
and judges.
Removed name column from DB for students, instructors, and judges

Added name method which returns a string of the first_name and last_name
variables seperated by a space for students, instructors, and judges
(this was done to preserve legacy code)

Updated forms to require a first/last name for user creation

Updated layout header to read "Not <first_name>?" instead of "Not
<full_name>?"

schema update (reflects DB change)