Refactor SeoPresentation - use translator as pattern

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | yes
| BC breaks?    | yes
| Deprecations? | yes
| Tests pass?   | see travis
| Fixed tickets | #58, #59 
| License       | MIT
| Doc PR        | TODO

Started this PR for the last big BC-break we have planed yesterday. 
Will combine the abstract and concrete implementation of SeoPresentation model first and
implement the translation keys later.