Upgrade Spring Batch dependency to 2.2.6

Fixes gh-720
Update Cloud Foundry deployment documentation

Update the Cloud Foundry section of the reference documentation to:

- Reflect the fact that the Cloud Foundry v6 CLI no longer has an
  interactive mode for application push.
- Update some of the CLI output.
- Change links to point to open-source CF docs instead of Pivotal
  commercial docs.
- Add a few links.

Fixes gh-718
Merge pull request #718 from scottfrederick/master

* pull718:
  Update Cloud Foundry deployment documentation