Add check for ordering of jenkins/jobs/projects.yaml

Example output of test:
$ tools/jenkins-projects-checks.py
Checking section 'OpenStack server projects'
Checking section 'OpenStack client projects'
Checking section 'oslo libraries'
Checking section 'Other OpenStack projects'
  Wrong alphabetical order: tempest, qa-specs
Checking section 'OpenStack API projects'
Checking section 'OpenStack documentation projects'
Checking section 'OpenStack development projects'
Checking section 'OpenStack infrastructure projects'
Checking section 'Stackforge projects'
Found errors in jenkins/jobs/projects.yaml!

This patch fixes the order so that it passes.
It also creates a new job to test this.

Change-Id: I36fd522261363494f07b57e40f0d9b943cf08841
Merge "Add check for ordering of jenkins/jobs/projects.yaml"