Unstable - Singleton Database()

Database() replaces the call to new H2(). Now only one instance of H2() can ever be returned. If it is the first time it is called it is instantiated, otherwise the same instance is returned. 

Can you please load up the profiler, and monitor how many H2() objects are loaded (maybe take a screenshot) before this implementation, and after, to prove we have increased performance????

Also, another thing I'd like to look at maybe during class this week is whether or not it is appropriate for us to apply the same thing to the getConnection() so that only one connection can be returned. Would that help performance? Would it hurt it? Let's find out!