[SPARK-1535] ALS: Avoid the garbage-creating ctor of DoubleMatrix

`new DoubleMatrix(double[])` creates a garbage `double[]` of the same length as its argument and immediately throws it away.  This pull request avoids that constructor in the ALS code.

Author: Tor Myklebust <tmyklebu@gmail.com>

Closes #442 from tmyklebu/foo2 and squashes the following commits:

2784fc5 [Tor Myklebust] Mention that this is probably fixed as of jblas 1.2.4; repunctuate.
a09904f [Tor Myklebust] Helper function for wrapping Array[Double]'s with DoubleMatrix's.