add a unique id to user objects, define a getter

www/common/cryptpad-common.js

@@ -44,6 +44,15 @@ define([
         }
         return;
     };
+
+    var getUid = common.getUid = function () {
+        if (store) {
+            if (store.getProxy() && store.getProxy().proxy) {
+                return store.getProxy().proxy.uid;
+            }
+        }
+    };
+
     var getRealtime = common.getRealtime = function () {
         if (store) {
             if (store.getProxy() && store.getProxy().info) {

www/common/fsStore.js

@@ -145,6 +145,12 @@ define([
             proxy.allowUserFeedback = true;
         }
 
+        if (typeof(proxy.uid) !== 'string' || proxy.uid.length !== 32) {
+            // even anonymous users should have a persistent, unique-ish id
+            console.log('generating a persistent identifier');
+            proxy.uid = Cryptpad.createChannelId();
+        }
+
         proxy.on('change', [Cryptpad.displayNameKey], function (o, n, p) {
             if (typeof(n) !== "string") { return; }
             Cryptpad.changeDisplayName(n);
@@ -156,6 +162,7 @@ define([
     var init = function (f, Cryptpad) {
         if (!Cryptpad || initialized) { return; }
         initialized = true;
+
         var hash = Cryptpad.getUserHash() || localStorage.FS_hash || Cryptpad.createRandomHash();
         if (!hash) {
             throw new Error('[Store.init] Unable to find or create a drive hash. Aborting...');