workaround to allow the plugin to use a proxyserver to access newrelic 

Although I don't think you can specify this in the config file, you can pass java properties to the plugin.
Now our New Relic MySQL Plugin is now sending data via our proxyserver! 

`$ java -Dhttps.proxyHost=proxyhost -Dhttps.proxyPort=8080 -jar newrelic_mysql_plugin-1.0.0.jar`
INFO: Using configuration file /opt/newrelic/plugins/newrelic_mysql_plugin-1.0.0/config/newrelic.properties
INFO: New Relic monitor started