Added modular DAL, updated gluon imports to new structure

gluon/scheduler.py

@@ -598,7 +598,7 @@ class Scheduler(MetaScheduler):
 
     def define_tables(self, db, migrate):
         """Defines Scheduler tables structure"""
-        from gluon.dal import DEFAULT
+        from gluon.dal.base import DEFAULT
         logger.debug('defining tables (migrate=%s)', migrate)
         now = self.now
         db.define_table(