Decide how to sanitize ntor-onion-key lines in bridge descriptors
Since upgrading to Tor 0.2.4.9-alpha, my bridges do not appear with correct information in https://onionoo.torproject.org/details?type=bridge:
- platform is either not present or still appears as "Tor 0.2.4.7-alpha on Linux". Note that, globally, no bridge is reported as running version 0.2.4.9, which is quite unlikely.
- advertised_bandwidth is either not present or 0,
- last_restarted is either not present or still the previous time from when previous version 0.2.4.7 was last restarted.
When downgrading to 0.2.4.7 (thanks to Debian snapshot), advertised_bandwidth moves away from 0, last_restarted and platform are correct again.