Better handling of user avatar. Don't create canvas el if there's no avatar.

Also, don't fetch vCards in rosterHandler. This could be very expensive for
large rosters, instead we'll fetch them when a user comes online.

converse.js

@@ -500,7 +500,6 @@
                     '<div class="chat-head chat-head-chatbox">' +
                         '<a class="close-chatbox-button">X</a>' +
                         '<a href="{{url}}" target="_blank" class="user">' +
-                            '<canvas height="35px" width="35px" class="avatar"></canvas>' +
                             '<div class="chat-title"> {{ fullname }} </div>' +
                         '</a>' +
                         '<p class="user-custom-message"><p/>' +
@@ -516,15 +515,18 @@
         render: function () {
             this.$el.attr('id', this.model.get('box_id'))
                     .html(this.template(this.model.toJSON()));
-
-            var img_src = 'data:'+this.model.get('image_type')+';base64,'+this.model.get('image');
-            var ctx = this.$el.find('canvas').get(0).getContext('2d');
-            var img = new Image();   // Create new Image object
-            img.onload = function() {
-                var ratio = img.width/img.height;
-                ctx.drawImage(img,0,0, 35*ratio, 35);
-            };
-            img.src = img_src;
+            if (this.model.get('image')) {
+                var img_src = 'data:'+this.model.get('image_type')+';base64,'+this.model.get('image'),
+                    canvas = $('<canvas height="35px" width="35px" class="avatar"></canvas>'),
+                    ctx = canvas.get(0).getContext('2d'),
+                    img = new Image();   // Create new Image object
+                img.onload = function() {
+                    var ratio = img.width/img.height;
+                    ctx.drawImage(img,0,0, 35*ratio, 35);
+                };
+                img.src = img_src;
+                this.$el.find('.chat-title').before(canvas);
+            }
             return this;
         },
 
@@ -1400,30 +1402,13 @@
                 if (!model) {
                     is_last = false;
                     if (index === (items.length-1)) { is_last = true; }
-                    xmppchat.getVCard(
-                        item.jid, 
-                        $.proxy(function (jid, fullname, img, img_type, url) {
-                            this.addRosterItem({
-                                jid: item.jid, 
-                                subscription: item.subscription,
-                                ask: item.ask,
-                                fullname: fullname,
-                                image: img,
-                                image_type: img_type,
-                                url: url,
-                                is_last: is_last
-                            });
-                        }, this),
-                        $.proxy(function (stanza) {
-                            console.log("rosterHandler: Error occured while fetching vcard");
-                            console.log(stanza);
-                            this.addRosterItem({
-                                jid: item.jid, 
-                                subscription: item.subscription,
-                                ask: item.ask,
-                                is_last: is_last
-                            });
-                        }, this));
+                    this.addRosterItem({
+                        jid: item.jid, 
+                        subscription: item.subscription,
+                        ask: item.ask,
+                        fullname: item.name,
+                        is_last: is_last
+                    });
                 } else {
                     if ((item.subscription === 'none') && (item.ask === null)) {
                         // This user is no longer in our roster