Persisted JMX connection not reestablished

With JMX persistent-connection="true", when application, which is sampled, becomes unavailable, metrics-sampler does not reconnect to the host on next sampling cycle, and metrics for the application do not get collected anymore. It seems like it should know that connection cannot be used anymore, and try to reestablish it.

Might be related to https://github.com/dimovelev/metrics-sampler/issues/8
