Fixed calculateDifference so it handles AM/PM Rollover properly

Also note, the PM takes about 6-7 minutes to answer a question instead
of the desired 10 minutes.

This affects my calculations for determining how long a Dev + Team Lead
have been WAITING to get their question answered. Scrolling to the very
bottom of TeamLead (Method, "answerQuestion()") you will be able to see
how I calculate wait time.

Currently I am assuming the PM will take 6 minutes to answer a question.
If PM is fixed so that he takes 10 minutes to answer, please change the
following:

timeWaitingForPm += ..... - 6)......

to
timeWaitingForPm += ..... - 10)......

Another important note, in the previous commit I changed Employee's
"doWork()" method so that it says sleep(10) INSTEAD OF sleep(5).