Document JSP deprecation per DEV-1058

• Include a JSP deprecation announcement in Magnolia 6.0 release notes.
• Explain how customers can include JSP modules in their own bundle if they want to keep using JSP.   
• Remove all JSP-related content from 6.0 docs.
• Edit wiki pages. Demote JSP options, promote alternative options.
  • https://wiki.magnolia-cms.com/display/WIKI/Reset+superuser+account
  • https://wiki.magnolia-cms.com/display/WIKI/Reset+all+passwords
  • https://wiki.magnolia-cms.com/display/WIKI/Backup+and+Restore+JSP+Scripts