matrix: make classes and methods package private in reference solution. Resolved the issue (#1083)
* made the class as the package private and the removed the public access modifier
* made the class as the package private and the removed the public access modifier
* removing the extra spaces
* removed the access modifier of the class Hamming and also the methods involving it
* added the private access modifier for the methods in Hamming class
Review markups. Changed assertion order, test names and position of Ignore in MatrixExercise. Changed Integer.valueOf to Integer.parseInt in Matrix. Changed String.split to using Pattern in Matrix.