v0.25.0

• Added Code of Conduct
• bigtable:
  • cbt: Support a GC policy of "never".
• errorreporting:
  • Support User.
  • Close now calls Flush.
  • Use OnError (previously ignored).
  • Pass through the RPC error as-is to OnError.
• httpreplay: A tool for recording and replaying HTTP requests
  (for the bigquery and storage clients in this repo).
• kms: v1 client added
• logging: add SourceLocation to Entry.
• storage: improve CRC checking on read.