fixed bug with saving due date in the database

- all hours would always be converted to 12 hr clock, so all times
would always be in AM even if specified as PM
added autosubmit on time out

- the exam will issue warnigns at 15 and  5 min intervals and auto
submit the exam when the time runs out (or about 10 seconds before so
that it has time to save the results before the server dissallows it to
submit any more results << this is temporary)