Enable coding-standards non-compliance to be a testbot failure condition on a per-project basis

Raising this issue as per https://www.drupal.org/node/1299710#comment-12052075 →

Apparently the testbot can be configured to halt on Coding Standards errors, but the integration with D.O doesn't provide a way of enabling that behaviour for a project.

I think adding such support would be a very valuable improvement.

For projects which are already coding-standards compliant, maintainers may likely find it desirable that any patches with coding standards violations are automatically flagged as failures so that the patch author can fix them without anyone else having to be involved. Anything which reduces the maintainer workload is a boon.