LOGBACK-818 add SSLSocketAppender and SimpleSSLSocketServer

This request provides an SSLSocketAppender and SimpleSSLSocketServer, supporting classes, and documentation updates. Touch points with the existing code base:

Extends SocketAppenderBase, overriding the getSocketFactory method.
Provides new ch.qos.logback.core.net.ssl package containing classes used to support appender configuration
Adds SSL types to the nested component types registry in -classic and -access
Adds new SSLSocketAppender to logback-classic and logback-access
Adds new SimpleSSLSocketServer to logback-classic
Modifies SimpleSocketServer to allow startup to be reused for SimpleSSLSocketServer