Add missing dirtiesContext in @CCMConfig of test

Add missing "dirtiesContext = true" configuration in @CCMConfig of
ControlConnectionTest.should_prevent_simultaneous_reconnection_attempts.

The test stops cluster nodes: ccm().stop(1), so it requires
"dirtiesContext = true". Even though the test class itself had
this option correctly set, the test method overwrote this configuration.

Depending on the order of tests, this could cause another test to fail,
as all of the nodes of cluster were removed.

Refs #170

Author: avelanarius

driver-core/src/test/java/com/datastax/driver/core/ControlConnectionTest.java

@@ -68,7 +68,7 @@ public class ControlConnectionTest extends CCMTestsSupport {
   static final Logger logger = LoggerFactory.getLogger(ControlConnectionTest.class);
 
   @Test(groups = "short")
-  @CCMConfig(numberOfNodes = 2)
+  @CCMConfig(numberOfNodes = 2, dirtiesContext = true)
   public void should_prevent_simultaneous_reconnection_attempts() throws InterruptedException {
 
     // Custom load balancing policy that counts the number of calls to newQueryPlan().