add onionoo version field to atlas/relay search
This is related to: https://trac.torproject.org/projects/tor/ticket/22488#comment:23
Goal: reduce the confusion for relay ops caused by false-positives of "you are running an outdated tor version" banner.
Below the platform field add the onionoo version field: https://metrics.torproject.org/onionoo.html#details_relay_version
Description: Version Tooltip text: Version of this relay as seen in the tor consensus
Based on the recent discussion on metrics-team ML I'm adding some ticket "metadata":
- This is a nice-to-have feature
- Would be nice to have it before 2019