services: update get_submissions to get_submission_results
services: add function to get all to-autojudge datasets for a task
ES: loads of changes
SS: loads of changes
SS: fail-proof against broken scorers and setups

Add immunity against broken scorers.
SS: Send correct datasets to RWS.

 - We only send results for the active dataset to RWS.
 - We also now re-send all results for a task when the dataset is changed.
SS: addition
CWS: loads of changes
CWS: Add immunity against broken scorers.
task versioning: add AdminWebServer support for managing datasets.
AWS: fix Manager and Testcase handlers
A mass of changes to use SubmissionResults where required.
Fix more places where SubmissionResult must be used.
AWS: Provide dataset-aware interfaces for submissions and tasks.
AWS: Only offer option to change datasets if we have more than one of them.
AWS: Fix bug when setting public flag in task interface.
AWS: Add support for cloning results when cloning datasets.
Add autojudge flag to datasets.
AWS: reinitialize SS after adding/removing Dataset or Testcase
task versioning: Move limits, task and score types into dataset.