Go SDK v1.9.1 released, with more effective event isolation

libhoney-go v1.9.1 has been published, now with Client objects for more effective event isolation.

This change may be particularly useful for users interested in isolating separate connections (or send queues) to Honeycomb: for example, if you'd like to take advantage of multiple libhoney.Configs (see godoc) in order to define custom transmission behavior.