rosie: handle QueryErrors and invalid prefix values

This adds handling to rosie go and rosie lookup for query errors as follows:

In case of an invalid prefix:
 * rosie go will now produce a dialog for invalid prefixes and not launch rather than just crashing out
 * rosie lookup will now produce a more helpful error message and exit rather than churning out traceback

QueryErrors and local suite statuses:
 * rosie go will now display a dialog and display empty results for the case of a QueryError raised by a get local suites query rather than crashing out.
 * rosie ls should produce a more helpful error message and exit rather than printing out traceback.

In addition, rosie go will print more helpful traceback when an error occurs on startup (at present the error details are lost).

Potentially closes #876.