ExitAuthority crash due to improper use of class SSLTestResult

strings "NoExit" and "NotStored" are passed for to the SSLTestResult constructor in a few cases, but the parent constructor doesn't expect a string:

if exit_obj:
 self.exit_node = exit_obj.idhex
 self.exit_name = exit_obj.nickname
 self.exit_ip = exit_obj.ip
 self.contact = exit_obj.contact