Fix how we detect grid settings presence in user session

..in case grid has filter settings only

tailbone/grids/core.py

@@ -586,7 +586,7 @@ class Grid(object):
         for key in ['page', 'sortkey']:
             if 'grid.{}.{}'.format(self.key, key) in self.request.session:
                 return True
-        return False
+        return any([key.startswith('grid.{}.filter'.format(self.key)) for key in self.request.session])
 
     def get_setting(self, source, settings, key, normalize=lambda v: v, default=None):
         """