Moved management package out of util package
JAVA-933: Registering MBean for each instance of DefaultConnectionProvider.
Domain of the ObjectName is now "org.mongodb.driver", whereas it used to be "com.mongodb".
Also, there is no way to support the ConnectionPoolStatisticsBean from the 2.x MXBean version,
so it's been dropped.  May add something equivalent, but in a different MBean, at a later date.
Remove race conditions from a few tests
JMX