Bump version to 0.6.6

Also updates the CHANGELOG while we're at it.

Change-Id: I9f6492bf2eaa60513e434cfa257519979a34966e
Reviewed-on: https://gerrit.causes.com/19950
Tested-by: jenkins <jenkins@causes.com>
Reviewed-by: Joe Lencioni <joe.lencioni@causes.com>