Added hostname trusted check for redirects.

Previously, redirect happened without checking if the hostname is
trusted. A sanity check to confirm the hostname is trusted prior to
redirection has now been added.

This can partly be considered as a fix to a security issue.

This is the second alpha release of this module.

Changes:

* Added support for link rewriting in addition to redirection.
* Removed Path Redirect entity type as the functionality is covered by
the Route Redirect type.
* Some refactoring of the code. In particular, oved the functionality of
matching an a DomainRouteRedirect entity into a separate service called
domain_route_redirect.matcher.