fixed some unicode issue

tools/memory.py

@@ -97,7 +97,7 @@ class Param():
     def save_xml(self, file):
         """Save parameters template to xml file"""
         with open(file, 'wb') as xml_file:
-            self.dom.writexml(xml_file)
+            xml_file.write(self.dom.toxml('utf-8'))
 
     def save_data(self, file):
         """Save parameters data to file"""

tools/xml_tools.py

@@ -73,7 +73,7 @@ def tupleList2dataForm(values):
 
 def paramsXml2xmlUI(xml):
     """Convert the xml for parameter to a SàT XML User Interface"""
-    params_doc = minidom.parseString(xml)
+    params_doc = minidom.parseString(xml.encode('utf-8'))
     top = params_doc.documentElement
     if top.nodeName != 'params':
         error(_('INTERNAL ERROR: parameters xml not valid'))