Single fog connection defaults in erb

As discussed in https://github.com/cloudfoundry/cf-release/pull/232 single `fog_connection` with the default for `local_root` in the templates.
If this PR gets merged the following PRs can be closed:
* [Use single fog_connection hash for ccng (second attempt)](https://github.com/cloudfoundry/cf-release/pull/236)
* [Add ceph as blobstore via s3 api](https://github.com/cloudfoundry/cf-release/pull/230)
* [Add AWS S3 region configuration option in ccng template](https://github.com/cloudfoundry/cf-release/pull/225)