fix missing sstats binds

modules/sstats/sstats.js

@@ -186,8 +186,8 @@ var sstats = function(dbot) {
                     });
                     this.db.del('user_stats', oldUser.id, function() {});
                     this.db.save('user_stats', newUser.id, function() {});
-                });
-            });
+                }.bind(this));
+            }.bind(this));
 
             this.db.scan('tracked_words', function(tWord) {
                 if(_.has(tWord.users, oldUser.id)) {
@@ -199,7 +199,7 @@ var sstats = function(dbot) {
                     delete tWord.users[oldUser.id];
                     this.db.save('tracked_words', tWord.word, tWord, function() {});
                 }
-            });
+            }.bind(this));
         }.bind(this));
     }.bind(this);
 };