added methods to add datasource and archive definition using RRDTool's syntax (DS:... RRA:...)
added methods to add datasource and archive definition using RRDTool's syntax (DS:... RRA:...)

OpenNMS/jrobin,OpenNMS/jrobin,roskens/jrobin,roskens/jrobin,OpenNMS/jrobin,OpenNMS/jrobin,roskens/jrobin