Add url_pattern to zuul.conf
Add url_pattern to zuul.conf

If a url_pattern is set, zuul will use it to generate a link to the logs
in success and failure messages.

Signed-off-by: K Jonathan Harker <8bfb1d549c776cc560071612e8edad51f4ea3c7c@ibm.com>

BonnyCI/hoist,BonnyCI/hoist,jamielennox/hoist,SpamapS/hoist,SpamapS/hoist,jamielennox/hoist