Mockery::hasSubstrings() matcher

Use as Mockery::hasSubstrings('needed substring', 'another needed substring')

I wrote the NonMatchingCase test in a different way than the other tests, because it seems to me that there's something wrong.  If you change, for instance, the third call to `foo()` in `testHasKeyConstraintNonMatchingCase()`, to `$this->mock->foo(1, array('a'=>1))`, the test still passes; I think it should fail?