Revert "Fix bug in prevention against concurrent retries (JAVA-449)."

This reverts commit 4e3b33cf3e5b83cb39cc53cc9bd53d48b51cfb01.
Revert "Prevent concurrent retries of the same query (JAVA-449)."

This reverts commit c105d1217f71394ce166aa808d14705a35ae230b.
Handle race between query timeout and completion (JAVA-449, JAVA-460, JAVA-471).
Update POM version in readme.
Fix DCAwareRoundRobinPolicy datacenter auto-discovery (JAVA-496).