Consider updating to support metrics 4.x

[davidh87]

Cassandra driver 3.7.x doesn't work with metrics 4.x - the JMXReporter class has moved in metrics making it incompatible.

https://docs.datastax.com/en/developer/java-driver/3.5/manual/metrics/ details how to address this; disabling the JMX reporter when constructing the cluster and then optionally, explicitly setting up JMX reporting if desired.

I'm unsure if users of this library rely on the JMXReporter behaviour, so unsure whether to simply disable it always, or if there is a need to add support to optionally enable it.