#489 New rule: JUnit tests should not contain control statements

[Elliotte Rusty Harold]

Most of the time JUnit tests should not contain control statements: if, while, for, etc. This usually indicates that the test is either:

1. Not always testing what it's supposed to be testing
2. Is not really a unit test.

I propose a new rule to flag such test cases. I may play around with writing this test myself.