fixed scheduler rollback typo, thanks Niphlod

VERSION

@@ -1 +1 @@
-Version 1.99.7 (2012-04-22 20:26:53) dev
+Version 1.99.7 (2012-04-23 11:26:23) dev

gluon/scheduler.py

@@ -413,7 +413,7 @@ class Scheduler(MetaScheduler):
                 db.commit()
                 break
             except:
-                db.rollback
+                db.rollback()
         logging.info('new task %(id)s "%(task_name)s" %(application_name)s.%(function_name)s' % task)
         return Task(
             app = task.application_name,