Added OpSubRegion2
Added first cut of OpResize (2D/3D only)
OpResize: Support 5D data.
cleanup.
OpResize: Added simple progress reporting, but won't be accurate for multiple threads.
jsonConfig: Added new pseudo-type for roi tuples.
submodules: updated pydvid
dvid operators use DvidConnection instead of HTTPConnection.
OpInputDataReader: Added SubVolumeRoi slot.
OpMultiArrayMerger: Fixed result copy.
OpStackToH5Writer: Raise exception if the globstring looks bad.
OpMaskedWatershed:
- Discard seeds outside the mask
- When possible, convert to uint8 before watershed is performed.
- Support non-5d axis orders.
Merge branch 'input-preprocessing'

Conflicts:
	lazyflow/operators/ioOperators/opExportDvidVolume.py
	lazyflow/operators/ioOperators/opInputDataReader.py
submodules: Updated pydvid
OpExportSlot: Instead of providing a simple true/false flag to indicate a valid format selection, provide a descriptive error message.
OpDvidExportVolume:
- Write to an existing volume, but create a new one if it doesn't exist.
- Accept an optional roi slot for writing only part of the volume.
OpDvidVolume: Provide ram_usage_per_pixel metadata
BigRequestStreamer: When determining blockshape, if ideal_blockshape isn't available, still try to use ram_usage_per_pixel.
submodules: updated pydvid
fileLock: Added warning statements to the docstrings about NFS, and also about Windows.