remote OpH5Writer, replaced by OpH5WriterBigDataset.py
always print traceback of request exception
fixed axistags for stack loader
Merge pull request #84 from bheuer/master

stackload fix
Fix dirty propagation in MultiArrayStacker if stacking axis not present. Really return binary output from opFilterLabels. Correct insertDim in roi.
use traceback.format_exc() instean of sys.exc_traceback
notify signature or notify_failed to also include exception_info tuple
use new notify_failed function signature in tests
Moved OpH5WriterBigDataset to ioOperators.py (ilastik issue #251)