Make Jeopardy an implementing class of JeopardyInterface

The Jeopardy class now implements the JeopardyInterface interface,
so an instance of Jeopardy can be instantiated to work alongside
the JeopardyBoard class.

To that end, much of the code that was used to make Jeopardy a
static program has been removed and instead instance methods from
JeopardyInterface have been added.