Migrate optaplanner.org to gh-pages (and related simplifications)

Motivation: gh-pages is significantly faster than jboss managements. That affects page ranking on google and user counts. Many other jboss websites have already moved to gh-pages hosting.

Pre-requirements:

• None of this work can start until the JBake migration is 100% finished.

Requirements:

• HTTPS access must still work
• Automatically HTTPS certification renewal by the JBoss staff must still happen
  That includes automatic warnings if HTTPS certificates are about to expire to JBoss staff too. => Talk to velias or Vladimir or David.
• HTTP to HTTP redirect must still work
• If there is a no-www to www redirect, that must still work.
• optaplanner.com to optaplanner.org redirect must still work. HTTP and HTTPS
• The 301 redirects mus still work. For example https://www.optaplanner.org/community/forum.html must end up on the getHelp.html page. There are 4 htaccess files with several 301 redirects each.

Out of scope for this ticket?

• docs.optaplanner.org - although it might affect the way gh-pages is set up...