Use CAReduceDtype{add} instead of CAReduce{add}

A test was using CAReduce{add} instead of Sum, so the accumulation
dtype could not be set.

Also fixed CAReduceDtype.make_node to allow use of CAReduceDtype{Add}
directly, instead of Sum.
Print actual command used in nightly build
Merge pull request #1260 from lamblin/test_careduce_add

Test careduce add