Do not use == to compare for chagned values in setValue

As discussed, rather use the 'is' operator.
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
allow ArrayLike destination to be h5py.Group

fixes ilastik/ilastik#240
Added OpWrapSlot.
Moved OpH5WriterBigDataset to ioOperators.py (ilastik issue #251)
remove test for removed OpH5Writer
Merge pull request #85 from christophdecker/master

 Moved OpH5WriterBigDataset to ioOperators.py (fixes #251)
missing import
remove deprecated API
remove obsolete code
fix import