More datamodel regression test comments and cleanup

bindings/java/test/org/sleuthkit/datamodel/BottomUpTest.java

...s/java/test/org/sleuthkit/datamodel/CPPtoJavaCompare.java

bindings/java/test/org/sleuthkit/datamodel/CrossCompare.java

...java/test/org/sleuthkit/datamodel/DataModelTestSuite.java

bindings/java/test/org/sleuthkit/datamodel/ImgTraverser.java

...ava/test/org/sleuthkit/datamodel/SequentialTraversal.java