[sqllab] add support for results backends (#1377)

* [sqllab] add support for results backends

Long running SQL queries (beyond the scope of a web request) can now use
a k/v store to hold their result sets.

* Addressing comments, fixed js tests

* Fixing mysql has gone away

* Adressing more comments

* Touchups

caravel/assets/javascripts/SqlLab/components/DataPreviewModal.jsx

@@ -0,0 +1,58 @@
+import * as Actions from '../actions';
+import React from 'react';
+import { bindActionCreators } from 'redux';
+import { connect } from 'react-redux';
+import { Modal } from 'react-bootstrap';
+
+import ResultSet from './ResultSet';
+
+const propTypes = {
+  queries: React.PropTypes.object,
+  actions: React.PropTypes.object,
+  showDataPreviewModal: React.PropTypes.bool,
+  dataPreviewQueryId: React.PropTypes.string,
+};
+
+class DataPreviewModal extends React.Component {
+  hide() {
+    this.props.actions.hideDataPreview();
+  }
+  render() {
+    if (this.props.showDataPreviewModal && this.props.dataPreviewQueryId) {
+      const query = this.props.queries[this.props.dataPreviewQueryId];
+      return (
+        <Modal
+          show={this.props.showDataPreviewModal}
+          onHide={this.hide.bind(this)}
+          bsStyle="lg"
+        >
+          <Modal.Header closeButton>
+            <Modal.Title>
+              Data preview for <strong>{query.tableName}</strong>
+            </Modal.Title>
+          </Modal.Header>
+          <Modal.Body>
+            <ResultSet query={query} visualize={false} csv={false} />
+          </Modal.Body>
+        </Modal>
+      );
+    }
+    return null;
+  }
+}
+DataPreviewModal.propTypes = propTypes;
+
+function mapStateToProps(state) {
+  return {
+    queries: state.queries,
+    showDataPreviewModal: state.showDataPreviewModal,
+    dataPreviewQueryId: state.dataPreviewQueryId,
+  };
+}
+function mapDispatchToProps(dispatch) {
+  return {
+    actions: bindActionCreators(Actions, dispatch),
+  };
+}
+
+export default connect(mapStateToProps, mapDispatchToProps)(DataPreviewModal);