[RFE] Migrate index.html to jinja2 file format

[evallesp]

Currently index.html[1] create a list of URLs for each worker available. Those URLs are not created on the fly.
A new DLRN instance Web page sourced will not work correctly without migrate the index.html to jinja2 file and take the URLs by the Ansible variables [2].

[1] https://github.com/rdo-infra/ansible-role-dlrn/blob/master/files/web/index.html
[2] https://github.com/rdo-infra/ansible-role-dlrn/blob/master/README.md#Variables