SIT-1749: handles a 4000 completion code.
SIT-1749: moved error methods to private.
SIT-1749: removed xml payload from ClientError message
Merge pull request #8 from sittercity/SIT-1749

SIT-1749: handles a 4000 completion code.
Merge branch 'master' into xml-version
Merge branch 'xml-version' into experian-error