Fix testr configuration

* Correct passing env vars in testr.conf.
* Use ZUUL_TEST_ROOT correctly when building the tempdir for
  the local git dir for tests.
* Remove some tabs from docs.
* Update test gearman server method override to match current gear.
* Make test_failed_changes more deterministic: this test
  occasionally failed due to races in the test.
* Update the fake logger configuration to match previous usage.

Change-Id: I1850b930e37d9a0fd2e9c8098052cf7df60576af
Reviewed-on: https://review.openstack.org/35404
Reviewed-by: Monty Taylor <mordred@inaugust.com>
Reviewed-by: Jeremy Stanley <fungi@yuggoth.org>
Reviewed-by: Clark Boylan <clark.boylan@gmail.com>
Approved: James E. Blair <corvus@inaugust.com>
Tested-by: Jenkins
Use daemon threads

Otherwise they can prevent exiting on timeout which confuses testr.

Change-Id: I239ab46f44fd09fe6b69fb70fdf4043e3c1daa67
Reviewed-on: https://review.openstack.org/35321
Reviewed-by: Monty Taylor <mordred@inaugust.com>
Reviewed-by: Jeremy Stanley <fungi@yuggoth.org>
Reviewed-by: Clark Boylan <clark.boylan@gmail.com>
Approved: James E. Blair <corvus@inaugust.com>
Tested-by: Jenkins
Add a JSON status test

And have the webapp listen on a configurable port to facilitate
parallel testing.

Start the webapp for every test to be consistent with production use.

Change-Id: I2f5c0d1669fac6db1604154ae9cd9d91fa073ba1
Reviewed-on: https://review.openstack.org/35553
Reviewed-by: Jeremy Stanley <fungi@yuggoth.org>
Reviewed-by: Clark Boylan <clark.boylan@gmail.com>
Approved: James E. Blair <corvus@inaugust.com>
Tested-by: Jenkins