Refs #3312 - Many fixes

- bring back webform file id (lost in refactoring)
- fix load_from_dd
- fix  getSchemaObjectsForDataflows to work with dtml :-(
- turn select obligation dropdown into a big select window
- secure mappings setter
- add temporary logging to catch 'delete all schemas' bug
- refactor some obfuscated code

TODO:
- remove has_webform property
- review the unit tests