Add JUnit-tests.

Add skeleton (boilerplate,.) test classes and test suite.
Remove source files for enums Rank and Suit.

Keep them inside the relevant classes instead.
Fixed JUnit test runner and test suite.

- Use test runner RunAllTests.java for running all tests.
- Specify which tests to be run i AllTests.java.
Updated JUnit test for Card.java

Might be stupid to compare with another instance of the class under
test. Direct string comparison should compensate some.