Add MasterView.listing flag, for templates' sake

tailbone/views/master.py

@@ -55,6 +55,7 @@ class MasterView(View):
     editable = True
     deletable = True
 
+    listing = False
     creating = False
     viewing = False
     editing = False
@@ -84,6 +85,7 @@ class MasterView(View):
         string, then the view will return the renderered grid only.  Otherwise
         returns the full page.
         """
+        self.listing = True
         grid = self.make_grid()
 
         # If user just refreshed the page with a reset instruction, issue a