Documentation updates

Among other things need to address the following:

- [ ] Now supports server sockets - blocking/nonblocking, SSL and plaintext
- [ ] Certificate support, which implies working with Java key manager/trust manager that can work with OpenSSL-formatted keys and certs
- [ ] Functional testing - this is no longer a spike, it's evolving into a design doc. We may get some degree of unit tests as well, before this is merged into Jython proper.
- [ ] Sporadic javax.crypto.BadPaddingException - see https://github.com/netty/netty/issues/1062, this seems to be a Java issue