Add integration tests for the JMX Metric Gatherer to cover SSL scenarios

[dmitchnewrelic]

Is your feature request related to a problem? Please describe. The JMX Metric Gatherer doesn't have any integration tests involving SSL.

Describe the solution you'd like Add integration tests that cover the following scenarios:

• SSL enabled for JMX, but not on the RMI registry
• SSL enabled for JMX including the RMI registry

Describe alternatives you've considered The alternative is to test this manually when needed.

Additional context This is related to issue #834 and PR #835

[breedx-splk]

@dmitchnewrelic Is this something you have interest and availability to take on?