message: Prevent FilterBox extra query
  closes
diff: @@ -1546,6 +1546,9 @@ class FilterBoxViz(BaseViz):
  credits = 'a <a href="https://github.com/airbnb/superset">Superset</a> original'
  def query_obj(self):
  + return None
  +
  + def filter_query_obj(self):
  qry = super(FilterBoxViz, self).query_obj()
  groupby = self.form_data.get('groupby')
  if len(groupby) < 1 and not self.form_data.get('date_filter'):
  @@ -1555,7 +1558,7 @@ class FilterBoxViz(BaseViz):
  return qry
  def get_data(self, df):
  - qry = self.query_obj()
  + qry = self.filter_query_obj()
  filters = [g for g in self.form_data['groupby']]
  d = {}
  for flt in filters:
  