ENH: adding test of DCMTK private dictionary
Created by: fedorov
See issue 4013 and #299
Philips phantom DWI dataset is included. The test runs dcmdump command, and looks for the description of tag (2001,1003), which should be DiffusionBFactor, and can only be recognized when private dictionary support is enabled in DCMTK.
@jcfr this test succeeds when I run --python-script from the binary install, but not from the build tree.