Re-factoring in support of https://issues.apache.org/bugzilla/show_bug.cgi?id=50360

Re-factoring in support of https://issues.apache.org/bugzilla/show_bug.cgi?id=50360
Move ad-hoc attribute handling from the ProtocolHandler to the Endpoint and expose the Endpoint to ServerSocketFactory objects so they can retrieve additional configuration if required. All default components now use explicit configuration rather than relying on the ad-hoc mechanism.
Ensure the hooks for alternative SSL implementations are in place (were partially removed).
Remove the hooks for alternative ServerSocketFactory implementations (had been hard-coded / half implemented for some time).
Make the sslEnabledProtocols attribute work with BIO as well.

git-svn-id: https://svn.apache.org/repos/asf/tomcat/trunk@1044058 13f79535-47bb-0310-9956-ffa450edef68