[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/index.jsx

@@ -0,0 +1,58 @@
+/* eslint camelcase: 0 */
+import React from 'react';
+import ReactDOM from 'react-dom';
+import { createStore, applyMiddleware, compose } from 'redux';
+import { Provider } from 'react-redux';
+import thunk from 'redux-thunk';
+
+import { now } from '../modules/dates';
+import { initEnhancer } from '../reduxUtils';
+import AlertsWrapper from '../components/AlertsWrapper';
+import { getControlsState, getFormDataFromControls } from './stores/store';
+import { initJQueryAjax } from '../modules/utils';
+import ExploreViewContainer from './components/ExploreViewContainer';
+import { exploreReducer } from './reducers/exploreReducer';
+import { appSetup } from '../common';
+import './main.css';
+
+appSetup();
+initJQueryAjax();
+
+const exploreViewContainer = document.getElementById('js-explore-view-container');
+const bootstrapData = JSON.parse(exploreViewContainer.getAttribute('data-bootstrap'));
+const controls = getControlsState(bootstrapData, bootstrapData.form_data);
+delete bootstrapData.form_data;
+
+
+// Initial state
+const bootstrappedState = Object.assign(
+  bootstrapData, {
+    chartStatus: null,
+    chartUpdateEndTime: null,
+    chartUpdateStartTime: now(),
+    dashboards: [],
+    controls,
+    latestQueryFormData: getFormDataFromControls(controls),
+    filterColumnOpts: [],
+    isDatasourceMetaLoading: false,
+    isStarred: false,
+    queryResponse: null,
+    triggerQuery: true,
+    triggerRender: false,
+    alert: null,
+  },
+);
+
+const store = createStore(exploreReducer, bootstrappedState,
+  compose(applyMiddleware(thunk), initEnhancer(false)),
+);
+
+ReactDOM.render(
+  <Provider store={store}>
+    <div>
+      <ExploreViewContainer />
+      <AlertsWrapper />
+    </div>
+  </Provider>,
+  exploreViewContainer,
+);