MAHOUT-1500: Implement H2O backend for Mahout Scala DSL

Barebone only, no logic yet. Compiles, tests fail with NotImplementedError

Signed-off-by: Anand Avati <avati@redhat.com>
MAHOUT-1500: Implement non algebraic parts of H2O bindings

Signed-off-by: Anand Avati <avati@redhat.com>
MAHOUT-1500: Implement Linear Algebra ops in H2O backend

Signed-off-by: Anand Avati <avati@redhat.com>