message: Query Browser: Allow "running" empty queries
  This fixes a bug where clearing a query input, then clicking the Run
  Queries button would have no effect. With this change, the query is
  correctly removed from the graph and the results table cleared.
diff: @@ -174,7 +174,7 @@ export default (state: UIState, action: UIAction): UIState => {
  const isEnabled = q.get('isEnabled');
  const query = q.get('query');
  const text = _.trim(q.get('text'));
  - return isEnabled && text && query !== text ? q.merge({query: text, series: undefined}) : q;
  + return isEnabled && query !== text ? q.merge({query: text, series: undefined}) : q;
  });
  return state.setIn(['queryBrowser', 'queries'], queries);
  }
  