1044686: Make serverurl parse error detailed again

The detail messages are populated by the exception mapper
now, but we need to use managerlib.handle_exception to
use it. ServerUrlParse errors were not using it, and
relied on the exceptions msg attribute, which is now
None.
Merge pull request #857 from candlepin/alikins/1044686_cli_handle_exception

1044686: Make serverurl parse error detailed again