Update redir.c

Added a new feature. Now it is possible per fqdn redirection, i.e, to redirect from site1 to site2,
just create a key 'site1' with text value 'site2', otherwise ,if key exists without value, client will be redirected to 'redirect_url'

 curl -v -d 'http://site2.org' -H "Content-Type: text/plain" http://<ip>:8098/buckets/blocked/keys/www.site1.org