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).
Add unit test for AbstractReconnectionHandler.
Change AbstractReconnectionHandler to yield to a previously running handler.

Also, expose a single Future in currentAttempt instead of switching in
the Futures from the executor. This makes it easier for clients to test
whether a handler is running at a given time.
Ensure control connection does not trigger concurrent reconnects (JAVA-497).
Refactor test classes.

- introduce custom AssertJ assertion for Cluster
- move waitFor methods to CCMBridge
Keep trying to reconnect on authentication errors (JAVA-472).
Expose close method on load balancing policy (JAVA-463).
Allow load balancing policy to trigger refresh for a single host (JAVA-459).
Move test method.
Make AbstractReconnectionHandler use a ListenableFuture.
Ensure failed reconnection attempts don't re-trigger onDown.
Expose an API to cancel reconnection attempts (JAVA-493).
Fix misplaced test class.
Fix NPE when a connection fails during pool construction (JAVA-503).
Log datacenter name in DCAware policy's init when it is explicitly provided (JAVA-423).
Disable test that causes timeouts on Jenkins.