Analytics (#582)

* gtm > ga

* Record pageviews in SPA

* Remove home-rolled tracking in favor of autotrack

* cleanup

app/components/ScrollToTop.js

@@ -0,0 +1,18 @@
+// @flow
+// based on: https://reacttraining.com/react-router/web/guides/scroll-restoration
+import { Component } from 'react';
+import { withRouter } from 'react-router-dom';
+
+class ScrollToTop extends Component {
+  componentDidUpdate(prevProps) {
+    if (this.props.location !== prevProps.location) {
+      window.scrollTo(0, 0);
+    }
+  }
+
+  render() {
+    return this.props.children;
+  }
+}
+
+export default withRouter(ScrollToTop);