AppenderTracker is now extends AbstractComponentTracker, removed support for sifting in Gaffer, tests pass

This eliminates duplicate life cycle management code in ContextBase and
LogbackValve.

This essentially mirrors the implementation in ContextBase.

SSLServerSocketAppender has an 'ssl' property of type SSLConfiguration.

This commit adds the new appender and modifies the JoranConfigurator
to include rules for SSL configuration types.

match start of content type so ex: application/x-www-form-urlencoded; charset=UTF-8 matches