Start using full-qualified ec2 id for the page url.

Note that this solution is half-baked since in this context
fqdn is just 'instance_name.' . FLAGS.wiki_instance_dns_domain
so the domain name is essentially hardcoded.

Will probably still work, though, presuming that wiki_instance_dns_domain
is properly set according to what region the nova host is in.

Change-Id: Ib50080a02ddcdc598ebd9bd1cfb227a195a6402e