Fail with status code and error message

* Capture both the status code and the original error message returned
  by BreweryDB.com. This helps tremendously when troubleshooting
  failures due to odd errors on their end (like the MySQL deadlock I
  triggred by firing off many concurrent requests).
Use status code and error message when failing
Merge pull request #18 from brewdega/fail_with_useful_error_message

Fail with status code and original error message.