update to keep up with shinken graphite module.py

change the sub regex of "self.multival.sub(r'.*', name)" to  self.multival.sub(r'.\1', name) to keep up with shinken graphite module.py about how to parse the perfdata. 
or otherwise, it will break with perfdata name "demo_123" with the wrong replaced one "demo" instead the correct one "demo.123", and finally result in "no data" in WebUI when graphite UI request the url.