CRM-5196 URL Template for MyOpenID is missing terminal slash

The OpenID login screen offers a list of providers. When clicking "MyOpenId", a template URl is shown, namely "http://yourname.myopenid.com" - when replacing yourname with the correct login name and hitting enter, the result is an error message, because the resulting URL is not a valid OpenID: it's missing the trainling slash. The template must be "http://yourname.myopenid.com/".

Alternatively, just add the slash automatically for sites known to need it. That would be much more convenient and avoids confusing the user. But it would mean maintaining a list of quirks of third party sites.