Allow serialization of a MetricsRegistry
1) Have com.codahale.metrics.Metric extend Serializable
2) Introduce a new marker interface, com.codahale.metrics.NoCopyMetric
3) Create custom serialization logic in MetricsRegistry that will
serialize all metrics that do NOT have the NoCopyMetric marker
4) Add some other NoCopy* signatures 
5) Modify some of the pre-creatable metrics that could not be serialized
to be marked as NoCopy