COMP: Syncronized and fixed bug in DCMTK path finding.

The cmake find package required the NO_MODULE option when specifying a system version
of DCMTK built outside of ITK.  This was needed to allow sharing a common DCMTK across
various tools.

git-svn-id: https://www.nitrc.org/svn/dtiprep/trunk@246 3db2834d-1276-0410-a171-f2f48b2634cc