Config files for ActiveMQ 5.8+

Adds support for ActiveMQ 5.8 and higher.  Earlier versions have different mBean structure, and could be adapted from these files.

There are two versions included here:

1. Basic monitoring -  These are server level metrics with the intent of having it supported as a "service" in Stackdriver with its own service page and named tab on the instance page.

2. Expanded monitoring - Includes the basic metrics and also some custom metrics for individual queues and topics that can be added to a custom dashboard for more detailed/targeted monitoring.  

The extended metrics are not included by default since they could be quite numerous on servers with a lot of configured destinations.  They could also be edited down to only the ones interesting to the user, or to queries for specific queue/topic names.

The typesNames elements in the JSON are inserted between the prefix and attribute names, so for a queue called "testqueue" you'd get the metricname "activemq.testqueue.QueueSize" for the QueueSize instance.