Fixed encapsulation problem when checking if a filename is versioned. The...

Fixed encapsulation problem when checking if a filename is versioned.  The check now properly uses Filename's IsVersioned() method instead of manually checking for question marks, which misses date versioned files.

git-svn-id: http://subversion.wr.usgs.gov/repos/prog/isis3/trunk@4061 41f8697f-d340-4b68-9986-7bafba869bb8