When casting dtypes, prefer numpy.asarray instead of ndarray.astype.  (The former avoids unecessary copies.)
added h5py to install requirements since it's required...
Reverted the following commit because we want the old and correct travis.yml back.

Revert "DO NOT MERGE TO MASTER: Removed .travis.yml from this branch because this branch currently fails and I don't want to fix it."

This reverts commit 3886eeec5b8875767cdd3455437629f932aa1894.

Conflicts:
	.travis.yml
travis bump
travis bump
travis
travis
travis
travis
fixed travis build
remove obsolete Struct slot type

plus some minor cleanups
change OpSegmentation to return uint8
graph.py: Fixed deprecation warning related to object.__new__
(What was I thinking?)
add return value validation check for arraylike
tighten result shape check
comments & cleanup
remove obsolete ArrayProvider class
tests: Use correct slicing in testOpRESTfulVolumeReader
rtype: SubRegion now supports copy.copy()
OpBlockedArrayCache: Avoid calling op.execute() directly, to ensure that the usual RequestExecutionWrapper is used.