v1.0.0

This is zap's first stable release. All exported APIs are now final, and no further breaking changes will be made in the 1.x release series.

Anyone using a semver-aware dependency manager should now pin to ^1.

Breaking changes:

• #366: Add byte-oriented APIs to encoders to log UTF-8 encoded text without casting from []byte to string.
• #364: To support buffering outputs, add Sync methods to zapcore.Core, zap.Logger, and zap.SugaredLogger.
• #371: Rename the testutils package to zaptest, which is less likely to clash with other testing helpers.

Bugfixes:

• #362: Make the ISO8601 time formatters fixed-width, which is friendlier for tab-separated console output.
• #369: Remove the automatic locks in zapcore.NewCore, which allows zap to work with concurrency-safe WriteSyncer implementations.
• #347: Stop reporting errors when trying to fsync standard out on Linux systems.
• #373: Report the correct caller from zap's standard library interoperability wrappers.

Enhancements:

• #348: Add a registry allowing third-party encodings to work with zap's built-in Config.
• #327: Make the representation of logger callers configurable (like times, levels, and durations).
• #376: Allow third-party encoders to use their own buffer pools, which removes the last performance advantage that zap's encoders have over plugins.
• #346: Add CombineWriteSyncers, a convenience function to tee multiple WriteSyncers and lock the result.
• #365: Make zap's stacktraces compatible with mid-stack inlining (coming in Go 1.9).
• #372: Export zap's observing logger as zaptest/observer. This makes it easier for particularly punctilious users to unit test their application's logging.

Thanks to @suyash, @htrendev, @flisky, @Ulexus, and @skipor for their contributions to this release.