Remove unsavable designer url

Related to: https://github.com/Polymer/designer/issues/35

I think [this Youtube comment](https://www.youtube.com/watch?v=djQh8XKRzRg&google_comment_id=z123hrxi0mqacxwx504cjv45fta0wdrpfu40k) is related as well. If it's ok, I'd like to remove the hash for now because it makes the tool seem broken and users following that screencast aren't able to save their work.