Add streaming support

[thewtex]

The ability to select a RequestRegion of interest.

[tbirdso]

The general case for reading requested regions from single-channel 3D volumes is addressed with #35 .

The following edge cases have not been investigated and could be tracked here or in a related issue:

• Stream multichannel image (may be addressed, untested)
• Stream images with axes permutations other then "z","y","x" (likely not yet addressed)
• Stream 2D or 4D images (may be addressed, untested)
• Inherit from itkStreamingImageIO and otherwise explore integrating with itkStreamingImageFilter
• Explore enlarging the requested region to reflect the chunk sizes that must be loaded into memory to read in the requested region
• Investigate whether requested regions can be read from compressed archives; if not then indicate that streaming from archives is not supported (which is likely)