Statuses/build API - allow local server url

The build status api requires a url parameter.

Currently this URL must be a 'valid' URL. We have a jenkins build server on premise that we access directly with ip:port , bitbucket rejects this.

So currently we just have to throw some random url that doesn't have anything to do with our build. It would be better if we didn't need a url at all, and even better if we can put in our local server ip and port.