I added SudokuSolvingAlgorithm interface, a test for byElimination imple...

I added SudokuSolvingAlgorithm interface, a test for byElimination implementation, and much more. Please see. I wrote everything the primitive way, no use of any framework for tests or controllers. I'd say that after we have at least two algorithms in place we can integrate JUnit and some technology like jsp for views. what do you think?