[BUGFIX] phpcr value format change exception try to delete property and rewrite it

__Tasks:__

- [ ] test coverage
- [ ] gather feedback for my changes


__Informations:__

| Q             | A
| ------------- | ---
| Tests pass?   | none
| Fixed tickets | #544
| BC Breaks     | no
| Doc           | none
the problem is the changing of content-types with same property-name ...
first it is a text_line and after changing template (or change xml-template) it is an internal link ... But i think a better way is to introduce a validate method in the content-type and call that before save.