Fix Unicode error on import

There was no reason that the resource extras needed to be ASCII-only, so
this allows them to accept Unicode values, which fixes a Unicode error
that was encountered with the latest data from OpenDataPhilly.

Also improves the --erase functionality of the script.
I don't know what this will look like in the log, but I imagine it will be without context. Perhaps a more explicit message like "Deleting packages from CKAN instance" would be better.