This commit create dedicated Jenkins jobs for 6.x for master branch and
PRs. This is required to allow having different test suites for 7.x and
6.x in a following PR.
This commit adds a new auth-token-credential-id entry in addition of auth-token-id for slack token.
This is due to a bug in JJB which requires having both entries to prevent having an empty authTokenCredentialId in job config.xml (https://storyboard.openstack.org/#!/story/2007953).
Add JJBB job definitions to the repo so they can be managed here.
Modified jobs so they will auto-generate the `inject-passwords` section
containing `VAULT_ROLE_ID`, `VAULT_SECRET_ID` and `VAULT_ADDR`.
