guessBrowser fix to recognize more GitHub URLs

[jglick]

Buglet noticed while testing jenkinsci/jenkins#2371.

@reviewbybees

[KostyaSha]

github-plugin had more fixes, probably compare regexpes?

[jglick]

github-plugin had more fixes

GitHubRepositoryName.URL_PATTERNS I suppose you mean?

As noted in a TODO comment nearby, I would really like to factor the guessing into an extension point. In the short term GithubWeb.GithubWebDescriptor could implement this, but that could perhaps be moved into github and share code with existing logic.

[ghost]

This pull request originates from a CloudBees employee. At CloudBees, we require that all pull requests be reviewed by other CloudBees employees before we seek to have the change accepted. If you want to learn more about our process please see this explanation.

[MarkEWaite]

I added support for ssh:// protocol form into the guesser and extracted the URL patterns out to a statically initialized array (as is done in github-pluign). I didn't add the extension point.