recursor: Add DNSSEC testing infrastructure and tests (#3741)

recursor: Add DNSSEC testing infrastructure and tests (#3741)

* Add rec dnssec test infra and initial tests

* Allow running an auth server

during the recursor regression tests.

Also add some boilerplate code so we can add DS records and root hints

* wip

* Add more infra to secure zones etc. wellKnown test passes, simple needs work

* Add own assertions, fix tests (all pass!)

* Hookup recursor DNSSEC tests to travis

* Add separate teardown classes

* Add a bogus zone

* Add tests for flag handling of the recursor

In preparation for #3682

And some new assertions

* Add flags test for bogus domains

* Lower startup delay

* refactor zones and keys

* Make pylint happy

* fix travis

* Disable WellKnown tests, they fail on travis

* WIP

* Add flag tests for insecure zone

* Change domain names to documentation names