Make user analytics optional (#59)

* Make user analytics optional

* Mention analytics in README

* Use analytics flag

pkg/dashboard/static/analytics.js

@@ -0,0 +1,58 @@
+const xhr = new XMLHttpRequest();
+xhr.onload = function () {
+    if (xhr.readyState === XMLHttpRequest.DONE) {
+        const status = JSON.parse(xhr.responseText);
+        if (status.Analytics && status.version !== "dev") {
+            enableDD(status.version)
+            enableHeap()
+        }
+    }
+}
+xhr.open('GET', '/status', true);
+xhr.send(null);
+
+
+function enableDD(version) {
+    (function (h, o, u, n, d) {
+        h = h[d] = h[d] || {
+            q: [], onReady: function (c) {
+                h.q.push(c)
+            }
+        }
+        d = o.createElement(u);
+        d.async = true;
+        d.src = n
+        n = o.getElementsByTagName(u)[0];
+        n.parentNode.insertBefore(d, n)
+    })(window, document, 'script', 'https://www.datadoghq-browser-agent.com/datadog-rum-v4.js', 'DD_RUM')
+    DD_RUM.onReady(function () {
+        DD_RUM.init({
+            clientToken: 'pub16d64cd1c00cf073ce85af914333bf72',
+            applicationId: 'e75439e5-e1b3-46ba-a9e9-a2e58579a2e2',
+            site: 'datadoghq.com',
+            service: 'helm-dashboard',
+            version: version,
+            trackInteractions: true,
+            trackResources: true,
+            trackLongTasks: true,
+            defaultPrivacyLevel: 'mask',
+            sessionReplaySampleRate: 0
+        })
+    })
+}
+
+function enableHeap() {
+    window.heap = window.heap || [], heap.load = function (e, t) {
+        window.heap.appid = e, window.heap.config = t = t || {};
+        let r = document.createElement("script");
+        r.type = "text/javascript", r.async = !0, r.src = "https://cdn.heapanalytics.com/js/heap-" + e + ".js";
+        let a = document.getElementsByTagName("script")[0];
+        a.parentNode.insertBefore(r, a);
+        for (let n = function (e) {
+            return function () {
+                heap.push([e].concat(Array.prototype.slice.call(arguments, 0)))
+            }
+        }, p = ["addEventProperties", "addUserProperties", "clearEventProperties", "identify", "resetIdentity", "removeEventProperty", "setEventProperties", "track", "unsetEventProperty"], o = 0; o < p.length; o++) heap[p[o]] = n(p[o])
+    };
+    heap.load("3615793373");
+}