JENKINS-18461 Add option for cloudstack clouds to not assign a public ip
address.

Use this option to use the internal ip address when running in an
isolated network with advanced networking.
Merge pull request #45 from spark404/nostaticnat

JENKINS-18461 Allow the user to not allocate a public ip address for a slave in a cloudstack cloud
[maven-release-plugin] prepare release jclouds-jenkins-2.4
[maven-release-plugin] prepare for next development iteration