New --repair option for configurable test runner

The option was missing from configurable-test-runner.sh, and we use it in a few tests.

I've added a --repair option that can take several values:
 - "show" tells the tests to display the changes that are to apply to the
    database. It is the equivalent of --showrepair of run-healthcheck.sh
 - "1", "yes", or "do" tells the tests to make the changes themselves

It works differently than in run-healthcheck.sh. In the latter, --repair and --showrepair could be used at the same time. I don't know if you guys want to preserve the original options