rosie go: fix File -> New Suite

This fixes a traceback in rosie go when `File -> New Suite...` is clicked:
```
Traceback (most recent call last):
  File "/opt/rose/lib/python/rosie/browser/main.py", line 656, in handle_create
    from_id, self.prefix)
  File "/opt/rose/lib/python/rosie/vc.py", line 310, in generate_info_config
    from_info_url = "%s/%s/rose-suite.info@%s" % (from_id.to_origin(),
```