Update ServiceProvider.php fix HTML::image() bug

Never done a pull request before but noticed that if you pass a url with the hostname to HTML::image() it gets returned with the base url twice which in turn means the image is not found.

Not sure if anyone else has found the same problem yet or whether it's just me, either way though it was worth looking at.

Removed protocol from config host to fix bug cause by passing full domain with protocol to HTML::image()