test HTTPS connection

This twig off the SSLStreamConnection branch in #479 adds a basic test of an HTTPS connection. It's based on TestHttpConnection.java, TestSSLStreamConnection.java, and the example code in HttpsConnection.java.

Since it's a branch off a branch, it'll contain that other branch's commits until we merge that branch. But the changes here are all in a single commit, 465e09c, so you can look at that one to see what's being added (the test code, a Python server and test web page, and an https/Protocol.java file from the reference implementation).