Set backend to 'Agg'.

moose-core/tests/python/test_rdesigneur.py

 """test_rdesigneur.py: 
-
 """
     
 __author__           = "Dilawar Singh"
@@ -11,8 +10,9 @@ __status__           = "Development"
 
 import sys
 import os
-import matplotlib as mpl
-mpl.use('Agg')
+import matplotlib 
+matplotlib.use('Agg')
+import matplotlib.pyplot as plt
 import numpy as np
 import moose
 import rdesigneur as rd