Define a route to /sitemap.xml

We would then populate this with sitemap XML.

Signed-off-by: Ealden Esto E. Escanan <ealden@odd-e.com>
Generate an empty sitemap.xml using xml-sitemap

Signed-off-by: Ealden Esto E. Escanan <ealden@odd-e.com>
Include top level URLs into sitemap.xml

Signed-off-by: Ealden Esto E. Escanan <ealden@odd-e.com>
Define sitemap as http://scrumprimer.org/sitemap.xml in robots.txt

Signed-off-by: Ealden Esto E. Escanan <ealden@odd-e.com>