refactoring out unused methods and public method, moving together

more refactoring removing of public methods; moving methods together as public, private

Merge branch 'removingmorepublicmethods'

changed public methods to private, renamed other methods

Delete CoinCalculatorImpl.java

renaming interface per Uncle Bob, removing public methods

adding polymophic vending items and implementations

Merge branch 'refactorVendItems'

adding VendingItems class

more refactoring out duplicate code;

committing main class

adding commit for tests

some refactoring done with moving calculation to interface; more work needed on duplication

Delete VendingMachineTests.class

Delete VendingMachine.class