python3: add support in IOGeoJSON and IOParallelXML tests

IO/GeoJSON/Testing/Python/TestGeoJSONWriter.py

+from __future__ import print_function
+
 import vtk, os, sys
 from vtk.test import Testing
 
@@ -40,13 +42,13 @@ for datasetString in testwrites:
      os.path.isfile(fname)):
     os.remove(fname)
   else:
-    print "Failed to write " + fname + " to file"
+    print("Failed to write " + fname + " to file")
     failed = True
   gw.WriteToOutputStringOn()
   gw.Write()
   gj = "['"+str(gw.RegisterAndGetOutputString()).replace('\n','')+"']"
   if len(gj) <= 1000:
-    print "Failed to write " + fname + " to buffer"
+    print("Failed to write " + fname + " to buffer")
     failed = True
 
 if failed:

IO/ParallelXML/Testing/Python/testParallelXMLWriters.py

+from __future__ import print_function
+
 import vtk
 from vtk.test import Testing
 from vtk.util.misc import vtkGetTempDir