Try to fix bug #986827, an exception is thrown on Windows when opening an imported presentation.

Fixes: https://launchpad.net/bugs/986827

openlp/plugins/presentations/lib/impresscontroller.py

@@ -42,6 +42,9 @@ import time
 if os.name == u'nt':
     from win32com.client import Dispatch
     import pywintypes
+    # Declare an empty exception to match the exception imported from UNO
+    class ErrorCodeIOException(Exception):
+        pass
 else:
     try:
         import uno