MAHOUT-1529 (d): moving core engine-independent tests logic to math-scala, spark module running them.
Source: dlyubimov/MAHOUT-1529d
This closes apache/mahout#28.

Squashed commit of the following:

commit 8d693b02e474ca1380c0e1cfa262ec4a47afeeae
Author: Dmitriy Lyubimov <dlyubimov@apache.org>
Date:   Mon Jul 14 13:03:13 2014 -0700

    minor style

commit f568736a35a8c76c6eb70694ce9feee09ff845dc
Author: Dmitriy Lyubimov <dlyubimov@apache.org>
Date:   Mon Jul 14 12:57:19 2014 -0700

    + license

commit d47e2dca693c147e6978a6c5e1fe42c1ab73ece3
Author: Dmitriy Lyubimov <dlyubimov@apache.org>
Date:   Mon Jul 14 12:55:36 2014 -0700

    + license

commit 61e6268d261c875781d430ca7861e0b345f485c3
Author: Dmitriy Lyubimov <dlyubimov@apache.org>
Date:   Fri Jul 11 11:31:44 2014 -0700

    style

commit c2406654c3fc7326b87848a23933cd4031a2c9a9
Author: Dmitriy Lyubimov <dlyubimov@apache.org>
Date:   Fri Jul 11 11:27:53 2014 -0700

    Initial test rearrangement. Pushing engine-independent logic to math-scala. Some renames.