[WIP] Refactoring to support 2.0

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | yes
| BC breaks?    | yes
| Deprecations? | no
| Tests pass?   | no
| Fixed tickets | #82, #83, #202
| License       | MIT
| Doc PR        | todo

Todo
---

* [ ] Create functional tests for PublishWorkflow listeners
* [ ] Create custom Loader to support PublishWorkflow
* [ ] Create a tag in the CoreBundle to support decorating services (which is support by Sf 2.5)
* [ ] Update SE
* [ ] Update sandbox
* [ ] Update cmf website
* [ ] Update docs