[FEATURE] including functionalities restore / delete to resource locator api and UI

including functionalities restore / delete to resource locator api and UI:

__Tasks:__

- [x] test coverage
- [ ] gather feedback for my changes
- [x] submit changes to the documentation
- [x] adding buttons to ui
- [x] add resource-locator repository
- [x] add resource-locator controller
- [x] adapt generate resource-locator to new api


__Informations:__

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | yes
| Tests pass?   | no => https://github.com/sulu-cmf/sulu/pull/110
| Fixed tickets | https://github.com/sulu-cmf/SuluContentBundle/issues/109
| Doc           | none
@wachterjohannes There is no need wrap the validate-method in an if-statement, because the validate method only gets called by the validation-library if neesValidation returns true.