add missing Normal on NoColors

closes  #1963

IPython/utils/coloransi.py

@@ -102,6 +102,7 b' class NoColors:'
     """This defines all the same names as the colour classes, but maps them to
     empty strings, so it can easily be substituted to turn off colours."""
     NoColor = ''
+    Normal  = ''
 
 for name, value in color_templates:
     setattr(NoColors, name, '')