fix axisartist.grid_finder.py to account for the api change of MaxNLocator

svn path=/trunk/matplotlib/; revision=8248

Author: leejjoon

lib/mpl_toolkits/axisartist/grid_finder.py

@@ -256,8 +256,9 @@ def __init__(self, nbins = 10, steps = None,
                  symmetric=False,
                  prune=None):
 
-        mticker.MaxNLocator.__init__(self, nbins, steps,
-                                     trim, integer, symmetric, prune)
+        mticker.MaxNLocator.__init__(self, nbins, steps=steps,
+                                     trim=trim, integer=integer,
+                                     symmetric=symmetric, prune=prune)
         self.create_dummy_axis()