Do not add title field to the navbar

For most services, no title is defined, so this is a no-op.

For those services where a title is defined (currently e.g. Zenodo and Rucio) this adds the title to the navbar as a link to "/". This isn't useful — it means that e.g. when deployed on sdc-dev these words link to https://sdc-dev.astron.nl/ which is a 404.

Closes esap-general#121 (closed).