JCLOUDS-534: Upgrade to Guava 17.0-rc2

Release notes:

https://code.google.com/p/guava-libraries/wiki/Release17
Using ServiceMix bundles for JSch and sshj agentproxy deps

Follow-up to 094f698f. See

* https://issues.apache.org/jira/browse/SMX4-1728
* https://issues.apache.org/jira/browse/SMX4-1729