FLOE-171: Upgraded metadata demo with the new infusion model relay system

@amb26, can you review this pull request, our first pilot of the new model relay.
Created a "Metadata Authoring Tool QA Test Plan" wiki page - http://wiki.fluidproject.org/display/fluid/Metadata+Authoring+Tool+QA+Test+Plan

Added a demos/html/index.md with a link to this test plan wiki page.