* Let Premoderator script add labels

* Fix JQ error

* Minor fixes

* Debug patch label output

* Try again

* Try again

* Try again

* Try again

* Try again

* Minor cleanup

* Update premoderator to fix Github API throttle

* Update premoderator script

Add exit codes and document the exit code.

* Fix indentation

- Attempt to clarify CI runs from contributors

Do not run unit-tests for master merges.
Fix the permissive "null" user.

Signed-off-by: Bogdan Dobrelya <bogdando@mail.ru>

For security and resources utilization reasons, do not auto-start CI
for opened/updated PRs.

A member of the kubernetes-incubator github org has first to approve
that the PR is reasonable to test by putting the "ci check this" into
the PR's comments.

If approved that way, the CI pipeline starts as always. Only the 1st step
of the pipeline is premoderatied, the rest will follow each over on
success.

Signed-off-by: Bogdan Dobrelya <bogdando@mail.ru>