EventIndex: Start the crawler only if it's configured to start.

src/indexing/EventIndex.js

@@ -120,7 +120,9 @@ export default class EventIndex {
             if (eventIndexWasEmpty) await addInitialCheckpoints();
 
             // Start our crawler.
-            this.startCrawler();
+            if (SettingsStore.getValueAt(SettingLevel.DEVICE, 'enableCrawling')) {
+                this.startCrawler();
+            }
             return;
         }
 

src/settings/Settings.js

@@ -490,5 +490,10 @@ export const SETTINGS = {
         supportedLevels: LEVELS_DEVICE_ONLY_SETTINGS,
         displayName: _td("How long should the crawler wait between requests"),
         default: 3000,
+    },
+    "enableCrawling" : {
+        supportedLevels: LEVELS_DEVICE_ONLY_SETTINGS,
+        displayName: _td("How long should the crawler wait between requests"),
+        default: true,
     }
 };