Fix opt warning/not moving to GPU some node.

Issue  #3429 - refactor some code to python 'with' statement

added comments to logistic regression example in the documentation

Bug fix: don't try to os.mkdirs on an empty directory

Fixed import of local pool submodule

Disable average_exc_pad pooling for cudnn v3

Update opt.py

Remove more warnings from the buildbot

See #3776

Renamed max_pool_2d to pool_2d and  DownsampleFactorMax to Pool

Fix blas detection on mac.

Bump version to 0.8.0.dev0

Fix buildbot

Also fix the flags test code so that it doesn't fail due to the mac bug.

before' make_thunk and help DebugMode work correctly.

LogSoftmax

More complete fix for the travis failures

Fix segfault