Allow user update slice title in visualize flow (#3466)

* 1. after user make sql query and visualize, allow user click title to update slice title, and create a new slice at the same time.
2. don't save new title if it is empty. Will still show old title.

* change saveSlice call response and update explore view

superset/assets/javascripts/explore/components/SaveModal.jsx

@@ -108,7 +108,7 @@ class SaveModal extends React.Component {
     this.props.actions.saveSlice(saveUrl)
       .then((data) => {
         // Go to new slice url or dashboard url
-        window.location = data;
+        window.location = data.slice.slice_url;
       });
     this.props.onHide();
   }
@@ -185,6 +185,7 @@ class SaveModal extends React.Component {
             {t('Add slice to existing dashboard')}
           </Radio>
           <Select
+            className="save-modal-selector"
             options={this.props.dashboards}
             onChange={this.onChange.bind(this, 'saveToDashboardId')}
             autoSize={false}