Using the jclouds version for Chef, rather than the project version

During releases, the reference should be to the released version of jclouds and jclouds-chef
Updating jclouds.version to 1.7.2

Preparing for the 1.7.2 jclouds-karaf release
[maven-release-plugin] prepare release jclouds-karaf-1.7.2-rc1