Re-adds the redirect on SiteNode move function

When a SiteNode is moved a redirect directive is created so that
the old URL redirects to the new. In order for the function to work
the composePageUrl method had to be modified.

In system redirect the string "{CONTEXT}" can be used to insert the
tomcat webapp context dynamically
Adds redirect suggestion feature to the error page
Merge pull request #64 from stenbacka/redirect-on-move

Redirect on move