FEATURE: Only load service worker for Android

TBD an interface for plugin to enable service workers on desktop if they need them

app/assets/javascripts/discourse/initializers/register-service-worker.js.es6

@@ -2,11 +2,27 @@ export default {
   name: 'register-service-worker',
 
   initialize() {
+    // only allow service worker on android for now
+    if (!/(android)/i.test(navigator.userAgent)) {
+
+      // remove old service worker
+      if ('serviceWorker' in navigator && navigator.serviceWorker.getRegistrations) {
+        navigator.serviceWorker.getRegistrations().then((registrations) => {
+          for(let registration of registrations) {
+            registration.unregister();
+          };
+        });
+      }
+
+    } else {
+
       const isSecure = (document.location.protocol === 'https:') ||
         (location.hostname === "localhost");
 
+
       if (isSecure && ('serviceWorker' in navigator)) {
         navigator.serviceWorker.register(`${Discourse.BaseUri}/service-worker.js`);
       }
     }
+  }
 };