add BitPerSampleUnit to the GUI

The BitsPerSampleUnit is missing in the GUI. It is hard-coded as Integer, because this is how it is also done in the other handlers. According to the specification of MIX, it can also be float. but this is not supported by jhove

jhove-apps/src/main/java/edu/harvard/hul/ois/jhove/viewer/RepTreeRoot.java

@@ -1274,6 +1274,10 @@ private DefaultMutableTreeNode nisoToNode(NisoImageMetadata niso) {
 			for (int i = 0; i < iarray.length; i++) {
 				nod.add(new DefaultMutableTreeNode(Integer.toString(iarray[i]),
 						false));
+				//BitsPerSampleUnit Integer is assumed, because of BitsPerSample
+				// According to the specification, it can also be float.
+				// This is currently not supported by jHove
+				nod.add(new DefaultMutableTreeNode("Integer"));
 			}
 		}
 		if ((n = niso.getSamplesPerPixel()) != NisoImageMetadata.NULL) {