MAHOUT-1580 Optimize getNumNonZeroElements() closes apache/mahout#17
MAHOUT-1573: More explicit parallelism adjustments in math-scala DRM apis; elements of automatic parallelism management

This closes apache/mahout#13.

Squashed commit of the following:

commit de03a6aa8361424ee8fb776f995fbe1b811e0ccd
Author: Dmitriy Lyubimov <dlyubimov@apache.org>
Date:   Wed Jun 18 14:22:46 2014 -0700

    doc

commit f399f7a4dc61905ef05d9944dbd2e5a4c31a654b
Merge: b02cf18 45d8803
Author: Dmitriy Lyubimov <dlyubimov@apache.org>
Date:   Wed Jun 18 14:18:35 2014 -0700

    Merge branch 'master' of https://git-wip-us.apache.org/repos/asf/mahout into MAHOUT-1573

commit b02cf18dac608e2f969a845efd7ee35a3a5bd0e0
Author: Dmitriy Lyubimov <dlyubimov@apache.org>
Date:   Wed Jun 18 14:18:03 2014 -0700

    switching to par(...) api

commit 06bb4bcdedb3c5aac50a44ddec3957f1ed12d808
Author: Dmitriy Lyubimov <dlyubimov@apache.org>
Date:   Fri Jun 6 23:05:12 2014 -0700

    pom fixes to fix tests (spark hadoop dependencies must precede that of mahout-math's for tests to run correctly)

commit 1e6e3f87ffab5897569fea94c643da2bdbb59e33
Author: Dmitriy Lyubimov <dlyubimov@apache.org>
Date:   Fri Jun 6 22:15:33 2014 -0700

    remove any special handling of Par in rewrites

commit 2f3b4f5bac901ec152453473d4982cb9b6e5d651
Author: Dmitriy Lyubimov <dlyubimov@apache.org>
Date:   Fri Jun 6 16:33:27 2014 -0700

    + auto_|| operator

commit 2733002f4b5db3d5114a440b03967d954a3738e9
Author: Dmitriy Lyubimov <dlyubimov@apache.org>
Date:   Fri Jun 6 15:56:26 2014 -0700

    explicit parallelism adjustment levers exact_|| and min_||

commit cf7f18b4af4ad043d2bdcefeeda15031fa018543
Author: Dmitriy Lyubimov <dlyubimov@apache.org>
Date:   Fri Jun 6 13:21:19 2014 -0700

    docs

commit 2f785109b9a52e748626ba46f5bc0a35ffc98e2c
Author: Dmitriy Lyubimov <dlyubimov@apache.org>
Date:   Fri Jun 6 13:02:11 2014 -0700

    Refactoring drmFromHDFS()
MAHOUT-1565 Remove mapreduce-job-specific MAHOUT_OPTS (nishkamravi via gcapan): this closes apache/mahout#4
MAHOUT-1561, MAHOUT-1568, MAHOUT-1569 text-delimited Spark readers and writers with drivers and a CLI for 'spark-itemsimilarity' closes apache/mahout#22
disabled ItemSimilarity test until we can work out how to run them without MAHOUT_HOME and SPARK_HOME being set
MAHOUT-1541, MAHOUT-1568, MAHOUT-1569 fixed a build test problem, drivers have an option new to not search for MAHOUT_HOME and SPARK_HOME
Merge branch 'master' of https://git-wip-us.apache.org/repos/asf/mahout
MAHOUT-1541 backed out compatability with legacy Item Similarity, now outputs raw LLR scores
MAHOUT-1541, MAHOUT-1568, added option to ItemSimilarityDriver to allow output that is directly search engine indexable, also some default schema's for input and output of TDF tuples and DRMs
MAHOUT-1583: cbind() operator for Scala DRMs
This closes apache/mahout#20

Squashed commit of the following:

commit 1baf3fcebf2cd49eb6487afe4eaed689653a3562
Merge: 41f0671 9bfb767
Author: Dmitriy Lyubimov <dlyubimov@apache.org>
Date:   Mon Jul 7 12:32:34 2014 -0700

    Merge branch 'master' into MAHOUT-1583

commit 41f0671c9ccca81883475437fe18056563c1f8ac
Author: Dmitriy Lyubimov <dlyubimov@apache.org>
Date:   Mon Jul 7 12:27:26 2014 -0700

    Adding assignment time comparison test

commit 6e115c87639ffb111b2e089d7ecdf0eaeecbb02b
Author: Dmitriy Lyubimov <dlyubimov@apache.org>
Date:   Mon Jun 16 18:42:42 2014 -0700

    + Licenses.

commit d3e905b5a92735822efe717f8b7a57c80bc56478
Author: Dmitriy Lyubimov <dlyubimov@apache.org>
Date:   Mon Jun 16 18:09:59 2014 -0700

    initial writeup
MAHOUT-1529: third collection of various edits against private branch

Squashed commit of the following:

commit 4328aae135bc56c02b944c21af2cfd6629b262bf
Author: Dmitriy Lyubimov <dlyubimov@apache.org>
Date:   Mon Jul 7 13:13:26 2014 -0700

    Various 1529-related stuff collected from private fork