Re-add import required for importing contests
Provide defaults for score_precision. (marginal improvement of UX)
Improve resilience and debugging in the face of failure.

Fixes a print in EvaluationService.py which would succeed if true, but throw an
exception on failure (because data["success"] is not valid, as data can be
None).
cmstestsuite: print stack trace on failure
Fixed bug that caused AWS errors when rescoring submissions
Fix AWS when viewing evaluated but not scored submissions.

If a submission has not been scored, s.score_details is not valid. The template
just needs to wait until they have been scored.
Remove unused get_encryption_alphabet from Cryptographics
Always log stdout/stderr somewhere.

If launched with /dev/null as our terminal, redirect stdout and stderr to our
logfile. Otherwise, useful information (e.g. backtraces on a crash) can be lost
forever.
Adding the new contributors to the AUTHOR file.
OutputOnly task type look at parameter to decide the comparator.

Previously, the task type parameter for deciding if the task used a
white diff or a comparator was ignored and the decision taken from the
presence or absence of a manager with any name.

Now, the decision is taken looking at the parameter and we require the
manager to be called checker (to avoid hard-to-debug errors).
Improvements to the documentation and some comments.