Remove support for Python 2. Misc fixes.

Misc cleanup

Merge branch 'travis'

Add Travis build status

Misc explanation

Try to override timeout exit code

Use "reduction='elementwise_mean'" instead of "size_average=True"

Use tensor.item() instead of tensor.data[0]

Use stable PyTorch version.

Update timeout

Add timeout for long-running tests

Bug fix for size mismatch issue occurred when using recent PyTorch.

Merge pull request #4 from esvhd/py36_fix

Fixed missing pytorch.

fix import for python 2.x