fixes issue #11: JVM Used Heap Calculation
fixes issue #11: JVM Used Heap Calculation

Juan-Moreno/sensu-plugins-java,Juan-Moreno/sensu-plugins-java,Juan-Moreno/sensu-plugins-java,sensu-plugins/sensu-plugins-java,sensu-plugins/sensu-plugins-java,sensu-plugins/sensu-plugins-java