Version 1.9.0 (2016-05-16)

New Features:

• Add support for custom offset manager retention durations
  (#602).
• Publish low-level mocks to enable testing of third-party producer/consumer
  implementations (#570).
• Declare support for Golang 1.6
  (#611).
• Support for SASL plain-text auth
  (#648).

Improvements:

• Simplified broker locking scheme slightly
  (#604).
• Documentation cleanup
  (#605,
  #621,
  #654).

Bug Fixes:

• Fix race condition shutting down the OffsetManager
  (#658).