MAHOUT-1610 [TESTS] Update tests to pass in Java 8

Right now, several tests don't seem to pass when run with Java 8 (at least on Java 8). The failures are benign, and just due to tests looking for too-specific values or expecting things like a certain ordering of hashmaps.

The tests can easily be made to pass both Java 8 and Java 6/7 at the same time by either relaxing the tests in a principled way, or accepting either output of two equally valid ones as correct.

(There's also one curious compilation failure in Java 8, related to generics. It is fixable by changing to a more explicit declaration that should be equivalent. It should be entirely equivalent at compile time, and of course, at run time. I am not sure it's not just a javac bug, but, might as well work around when it's so easy.)