refactor publish workflow to use security, cleanup configuration

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | yes
| BC breaks?    | yes
| Deprecations? | no
| Tests pass?   | the same as master
| Fixed tickets | #45, #49, #58
| License       | MIT
| Doc PR        | https://github.com/symfony-cmf/symfony-cmf-docs/pull/171

This is a vast simplification and moving towards standard symfony concepts that people already know. If we do this, we get a lot more flexible.

See https://github.com/symfony-cmf/BlogBundle/pull/25/files for an example of how to use this in other bundles. Once we agree on merging this, i will push an updated sandbox and the other affected bundles.