Handle SSL 2.0 connections gracefully

Detect and report unsupported SSL 2.0 connections as such, rather than
a generic unparseable client connection.
Merge pull request #104 from dlundquist/ssl20-compatibility

Handle SSL 2.0 connections gracefully
Rename name pattern in table backends

This is been a regular expression pattern since 072a9f03, and I've
found myself assuming it always contains a hostname so fix the name.

Update ARCHITECTURE.md with name change too
Add missing include to cfg_parser.c
wip
listener reference counting framework