Chapter 14: Added private class Pair to the Bank class, added testArrayEquals, testIdentityRate, added Hashtable to Bank to keep rates.
Chapter 15: added testMixedAddition - DOES NOT COMPILE! Commited for educational purposes.
Chapter 15: added testMixedAddition - made it compile and run.
Chapter 15: changed testMixedAddition to original state, made it compile and run.