We have a reasonably stable revison now, and have some future features
in the pipeline, so a good point for a 2.2 release.

Thanks to our contributors for this version:

 * Andrew Jeffery
 * Jeremy Kerr
 * John Chung
 * Khang D Nguyen
 * Khem Raj
 * Marc Olberding
 * Matt Johnston
 * Thu Nguyen
 * Timon Liu

Signed-off-by: Jeremy Kerr <jk@codeconstruct.com.au>