Plugin template for curl_json

This is template plugin for parsing values from curl_json.
Test set was: https://collectd.org/wiki/index.php/Plugin:cURL-JSON/phpfpm
Unfortunately it is need a special handling for COUNTER type values, so i dunno how to write universal plugin. Because there is no type (COUNTER/GAUGE) of value, as for 'tail' plugin in the rrd file name.