Catching up in CHANGES.txt
WHIRR-738. Create a service for Druid.

Contributed by Russell Jurney
WHIRR-748. Move to jclouds 1.6.2-incubating.
WHIRR-751. Improve Kerberos service
Update CHANGES.txt for WHIRR-751
WHIRR-753 - Move to jclouds 1.7.0, use security group extension