README,man: Update url to Piglit's website

Signed-off-by: Chad Versace <chad.versace@linux.intel.com>
Update urls to Waffle website and release files

Website and release files have moved from "http://waffle-gl.github.io"
to "http://www.waffle-gl.org".

Signed-off-by: Chad Versace <chad.versace@linux.intel.com>