MAHOUT-1529: Move dense/sparse matrix test in mapBlock into spark/

In h2o engine, the Matrix provided to mapBlock() is an instance of
"H2OBlockMatrix extends AbstractMatrix", and neither a DenseMatrix
nor SparseMatrix. H2OBlockMatrix is a 0-copy virtual Matrix exposing
just the partition's data (created at almost no expense), and creates
a copy-on-write Matrix only if modified by the blockmapfunction.

So these two tests are failing with h2obindings. Hence moving these two
tests into spark module.

Signed-off-by: Anand Avati <avati@redhat.com>