Merge branch 'stable-2.8'

* stable-2.8:
  Update release notes with recently made changes
  Buck: extend the tool chain to support unsigning JARs
  Update jgit to 3.1.0.201310021548-r
  Fixing jdbc code: correct Statement closing
  Remove unnecessary imports
  Print error message to log when plugin loader fails to close JAR file
  Document how plugins can listen to stream-events

Change-Id: I2f0051fdf065a6b0170294c6f9dfbef1ea4018ab