Revert "JCLOUDS-653: Upgrade to Guava 18.0"

This reverts commit 6d63489009c0d367a91aee9808b2d323917008a9.
Revert "JCLOUDS-653: Upgrade to Guava 18.0-rc1"

This reverts commit 178cb520e877e86be1ac35b37ed9f25cb36c5c56.