MAHOUT-1597: A + 1.0 (element-wise scala operation) gives wrong result if rdd is missing rows, Spark side (dlyubimov)
This closes apache/mahout#33

Squashed commit of the following:

commit 9038b2c248ec163e0ff85dd37cb109345b3bbb9d
Author: Dmitriy Lyubimov <dlyubimov@apache.org>
Date:   Mon Jul 28 10:22:30 2014 -0700

    in-place performance enhancement at the risk of side-effects, for now

commit 35c873cceeda87b7b212677bffc0a21877932deb
Author: Dmitriy Lyubimov <dlyubimov@apache.org>
Date:   Tue Jul 22 15:34:00 2014 -0700

    CBind test tweak

commit 005aeccd353faeb59f2ddb2003f393a603978edb
Author: Dmitriy Lyubimov <dlyubimov@apache.org>
Date:   Tue Jul 22 15:33:18 2014 -0700

    Cbind test

commit 57f669a7d50097a5a816ce13ca8230f6c6742b65
Author: Dmitriy Lyubimov <dlyubimov@apache.org>
Date:   Tue Jul 22 14:57:57 2014 -0700

    Also fixing `A ew B` with missing rows operands

commit 2063c5ccaf88bf31d7f5c1dd3d1650925c4dfd58
Author: Dmitriy Lyubimov <dlyubimov@apache.org>
Date:   Tue Jul 22 14:12:56 2014 -0700

    style

commit 5d8e1407a7ea2535ae6d00701ed4f60390c1b30e
Author: Dmitriy Lyubimov <dlyubimov@apache.org>
Date:   Tue Jul 22 14:09:11 2014 -0700

    Orientation changing unary ops cannot produce missing rows

commit c9ac3be81ed464ccc4d440b8187e15efa9a21193
Author: Dmitriy Lyubimov <dlyubimov@apache.org>
Date:   Tue Jul 22 14:03:25 2014 -0700

    Tests, passing .

commit 1ff376b2ddd1bcbe61f896d14e27d7a413e7313c
Author: Dmitriy Lyubimov <dlyubimov@apache.org>
Date:   Tue Jul 22 13:23:14 2014 -0700

    Code up for lazy int-keyed missing rows fix

commit 746b3ddc6c0e7e8bb89ce591c32ba1b70ec688e6
Author: Dmitriy Lyubimov <dlyubimov@apache.org>
Date:   Tue Jul 22 11:25:57 2014 -0700

    WIP

commit 45642b65f3f1620a4e2187af4b2b54e26ce1c42e
Author: Dmitriy Lyubimov <dlyubimov@apache.org>
Date:   Mon Jul 21 18:19:37 2014 -0700

    WIP