test: refactor test-https-simple.js

This refactoring:

* eliminates the need for the external `curl` command
* speeds the test by running the two test requests simultaneously
* checks the type of error in the test that expects a failure
    (previously, any error type would cause the test to pass)

PR-URL: https://github.com/nodejs/node/pull/2433


Reviewed-By: Brendan Ashworth <brendan.ashworth@me.com>
Reviewed-By: Sakthipriyan Vairamani <thechargingvolcano@gmail.com>