Integrator should respect Harmattan's concept of "insignificant" test

Harmattan test infrastructure allows a testcase to be marked as "insignificant", which means that failures are reported but don't block integration.

Integrator has a similar mechanism which we refer to as the "blacklist".

Currently these are entirely separate, and we have the problem that a failing test in Harmattan may block integration, even if the test has already been marked as "insignificant" in the Harmattan test packages.

We must respect the "insignificant" marker in Harmattan tests so that a failing-but-insignificant test doesn't block integration.