Added special case to ArvadosModel#readable_by so that a name link going from a
readable group or user uuid confers permission to read the collection.  Added
unit test.
Add check to JobsController#create that collection output of a job is readable
by current user before attempting to re-use job.  Added unit test.
Fixed record symbolic name, comment based on feedback.
Merge branch 'origin-3442-no-reuse-job-when-output-unreadable' refs #3442
Merge branch 'origin/3443-read-collections-from-name-links' refs #3443

Conflicts:
	services/api/test/fixtures/links.yml
	services/api/test/functional/arvados/v1/groups_controller_test.rb