BUG: Fixed loading of DICOM image from files containing special characters

Got some DICOM files that contained a special character in the file names
and in the patient name.
Slicer failed to load them because lack of proper encoding before using
them.

Solution:

• Encode strings to latin1 before using them in VTK set functions.
• Encode file names to a byte stream before sending them to hashlib.

From: Andras Lasso <lasso@queensu.ca>

git-svn-id: http://svn.slicer.org/Slicer4/trunk@23868 3bd1e089-480b-0410-8dfb-8563597acbee