Strip versions from ibis paths

[pcapriotti]

This makes it possible to access external API endpoints not implemented in wire-server with a version prefix.

Checklist

• The PR Title explains the impact of the change.
• The PR description provides context as to why the change should occur and what the code contributes to that effect. This could also be a link to a JIRA ticket or a Github issue, if there is one.
• If HTTP endpoint paths have been added or renamed, the endpoint / config-flag checklist (see Wire-employee only backend wiki page) has been followed.
• changelog.d contains the following bits of information (details):
  • A file with the changelog entry in one or more suitable sub-sections. The sub-sections are marked by directories inside changelog.d.
  • If public end-points have been changed or added: does nginz need un upgrade?

[mdimjasevic]

I'm not too familiar with the templating language, but I assume you've checked the outcome in some way.