Fix GPU tests to not expect GpuSubtensors.
Maybe fix scan test?

I'm not sure what this test is expecting.  It seems to test that the gpu will magically work and optimize the graph even though we disable InputsToGpuOptimizer (which is obviously not the case).  I wonder why it passed before.  I wonder if this is the right fix.  I also wonder what is it testing exactly.

In any case it seems to pass now.
Merge pull request #2341 from abergeron/fix_buildbot

Fix buildbot error from #2329
Add print during unit test to help preventing timeouts
Merge pull request #2342 from abergeron/multi_fixes

Multi fixes (pieces of the multi-gpu code)
Merge pull request #2344 from carriepl/test_too_long

Add print during unit test to help preventing timeouts