Refactor cucumber helpers to set error and call extra callback
HTTP_DONE event should only reset body if buffers is filled
Add AWS.util.crypto.crc32()
Add CRC checking to DynamoDB requests

Disable CRC checking by setting 'dynamoDbCrc32' config setting to false:

  var db = new AWS.DynamoDB({dynamoDbCrc32: false});
Add newline to messages.feature