[Auth] Adds property "image" to InfoEntity

* If an image id is set in the entity the builder injects a relation entity
  to the contact image.
[Applications] Adds ability to forward an application via email.

* Adds new mail plugin "Forward"
* Adds a small forward email form to application detail page
  Currently this works only via ajax
Merge branch 'feature/Applications-forward_application_via_email' into develop