Primary changes:
- 17, return noop implementation if id is used for another meter type.
- 19, assume gauge is statistic tag is not set.
- 21, additional logging if GlobalRegistry does not start.
- 22, make gauge TTL consistent with Java client.
A comprehensive list of changes can be found in the commit log: https://github.com/Netflix/spectator-py/compare/v0.1.9...v0.1.11