Update to latest bundle standards

To be merged together with https://github.com/symfony-cmf/CreateBundle/pull/70

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | yes
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #29 
| License       | MIT
| Doc PR        | https://github.com/symfony-cmf/symfony-cmf-docs/pull/191

- [x] [General Bundle Standards](http://symfony.com/doc/master/cmf/contributing/bundles.html#general-bundle-standards)
- [x] > [File Naming](http://symfony.com/doc/master/cmf/contributing/bundles.html#file-naming)
- [x] > [Interface Naming](http://symfony.com/doc/master/cmf/contributing/bundles.html#interface-naming)
- [x] [Meta: README, CHANGELOG, etc](http://symfony.com/doc/master/cmf/contributing/bundles.html#meta-readme-changelog-etc)
- [x] [Persistence](http://symfony.com/doc/master/cmf/contributing/bundles.html#persistence)
- [x] [Configuration, Files and Formats](http://symfony.com/doc/master/cmf/contributing/bundles.html#configuration-files-and-formats)
- [x] [Testing Component Integration](http://symfony.com/doc/master/cmf/contributing/bundles.html#testing-component-integration)

http://symfony.com/doc/master/cmf/contributing/bundles.html

**TODO**
sync changed configuration with:
- [x] CreateBundle (cmf_media.manager -> cmf_media.persistence.phpcr.manager)
- [x] cmf-sandbox or CoreBundle? (basepath, enable persistence.phpcr)
- [x] documentation