MAHOUT-1529: completely abstracting away dssvd, dspca and dqr: introducing CacheHint enum

Squashed commit of the following:

commit 6c4bf1650f0e87d0d1fc5b9b23c94f6e3553b74d
Merge: a748e8b 0c5a754
Author: Dmitriy Lyubimov <dlyubimov@apache.org>
Date:   Tue May 6 18:20:36 2014 -0700

    Merge branch 'trunk' into MAHOUT-1529

commit a748e8b8be2ad7ce44af231147b236726704b561
Author: Dmitriy Lyubimov <dlyubimov@apache.org>
Date:   Tue May 6 18:19:35 2014 -0700

    MAHOUT-1529: completely abstracting away dssvd, dspca and dqr: introducing CacheHint enum

git-svn-id: https://svn.apache.org/repos/asf/mahout/trunk@1592933 13f79535-47bb-0310-9956-ffa450edef68