Merge branch 'master' into 'production'

Update model_core to remove import from obsolete module constants.

Bug fixed

See merge request !27

modules/plugin_event/model_core.py

@@ -6,7 +6,6 @@ import plugin_dbui as dbui
 
 
 from callbacks import INHIBIT_CASCADE_DELETE
-from constants import today
 from datetime import datetime
 from gluon import current
 from gluon.validators import IS_IN_DB