This icecast plugin captures a set of data similar to the "icecast2_"
and "icecast2_all" plugin. Sadly both are not configurable (manual
changes are required for target host and access credentials).
Additionally they use the rather old-fashioned (and password restricted)
xml status output.
This new plugin "icecast2_stats" (written from scratch) contains the
following notable differences:
* runs with Python 3
* supports a real "autoconf" and "suggest" interface
* is configurable (target host and port) via environment settings
* uses the json status output instead of the xml data
* contains no hard-coded values, names or patterns
