Build sign-in kiosk

[mikemolenda]

• [x] Sign in Form
• [x] Status Message: Complete Sign-In
• [x] Status Message: Partial Sign-In
• [x] Status Message: Guest Not Pre-registered
• [x] Status Message: Email Address Not Recognized
• [x] Status Message: User Already Signed In
• [x] Status Message: Event Ended
• [x] Status Message: Event Full
• [x] Add new user
• [x] Create welcome message for index.jsp if someone tries to open the kiosk without selecting an event