Use link field type for redirect target

[alexander-schranz]

Q	A
Bug?	no
New Feature?	no
Sulu Version	Specific version or SHA of a commit
SuluRedirect Version	Specific version or SHA of a commit
Browser Version	Browser name and version

Actual Behavior

Currently the redirect target is just a absolute url or absolute path.

Expected Behavior

It would be nice to redirect always to a specific page also when the page url changes. This could be done by using the link field type instead a text input.