Alter sample REGEXP to include file-schema URLs

[RalphCorderoy]

Emails here often contain file:///etc/passwd style URLs as we pass around references to local files and want to be able to open them by asking the desktop to use a suitable handler for the type of file. That request for http, etc., schemas works well with urlview(1), but the REGEXP doesn't cover the file schema. The url.conf.suse has an adjustment to do that, but packagers are sticking the sample in /etc/urlview/system.urlview and thus urlview's behaviour lags other programs, e.g. an X terminal that underlines file-schema URLs.