Checks if the terminal expected success state has been met
@return [Boolean]
function checkSuccess(resp) {
    if (!this.config.successPath) {
      return resp.httpResponse.statusCode < 300;
    }

    var r = AWS.util.jamespath.find(this.config.successPath, resp.data);

    if (this.config.failureValue &&
        this.config.failureValue.indexOf(r) >= 0) {
      return null; // fast fail
    }

    if (this.expectedValue) {
      return r === this.expectedValue;
    } else {
      return r ? true : false;
    }
  }