[clarity/consistency] rename /explorev2/ -> /explore/ (#2802)

* rename /explorev2/ -> /explore/

* add redirect for existing explorev2 urls

* fix long line

* remove extra line

* fix missed ref in spec

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

@@ -0,0 +1,80 @@
+import React from 'react';
+import PropTypes from 'prop-types';
+import { ControlLabel, OverlayTrigger, Tooltip } from 'react-bootstrap';
+import InfoTooltipWithTrigger from '../../components/InfoTooltipWithTrigger';
+
+const propTypes = {
+  label: PropTypes.string.isRequired,
+  description: PropTypes.string,
+  validationErrors: PropTypes.array,
+  renderTrigger: PropTypes.bool,
+  rightNode: PropTypes.node,
+};
+
+const defaultProps = {
+  validationErrors: [],
+  renderTrigger: false,
+};
+
+export default function ControlHeader({
+    label, description, validationErrors, renderTrigger, rightNode }) {
+  const hasError = (validationErrors.length > 0);
+  return (
+    <div>
+      <div className="pull-left">
+        <ControlLabel>
+          {hasError ?
+            <strong className="text-danger">{label}</strong> :
+            <span>{label}</span>
+          }
+          {' '}
+          {(validationErrors.length > 0) &&
+            <span>
+              <OverlayTrigger
+                placement="right"
+                overlay={
+                  <Tooltip id={'error-tooltip'}>
+                    {validationErrors.join(' ')}
+                  </Tooltip>
+                }
+              >
+                <i className="fa fa-exclamation-circle text-danger" />
+              </OverlayTrigger>
+              {' '}
+            </span>
+          }
+          {description &&
+            <span>
+              <InfoTooltipWithTrigger label={label} tooltip={description} />
+              {' '}
+            </span>
+          }
+          {renderTrigger &&
+            <span>
+              <OverlayTrigger
+                placement="right"
+                overlay={
+                  <Tooltip id={'rendertrigger-tooltip'}>
+                    Takes effect on chart immediatly
+                  </Tooltip>
+                }
+              >
+                <i className="fa fa-bolt text-muted" />
+              </OverlayTrigger>
+              {' '}
+            </span>
+          }
+        </ControlLabel>
+      </div>
+      {rightNode &&
+        <div className="pull-right">
+          {rightNode}
+        </div>
+      }
+      <div className="clearfix" />
+    </div>
+  );
+}
+
+ControlHeader.propTypes = propTypes;
+ControlHeader.defaultProps = defaultProps;