Fix metric value setting in GKE
Fix metric value setting in GKE

aegixx/heapster,andyxning/heapster,Stackdriver/heapster,bluebreezecf/heapster,shilpamayanna/heapster,jackzampolin/heapster,johanneswuerbach/heapster,saiwl/heapster,AlmogBaku/heapster,whuwxl/heapster,liubog2008/heapster,whuwxl/heapster,krzyzacy/heapster,adfin/statster,huangyuqi/heapster,taimir/heapster,luxas/heapster,bruceauyeung/heapster,andyxning/heapster,burmanm/heapster,saiwl/heapster,titilambert/heapster,bluebreezecf/heapster,jackzampolin/heapster,taimir/heapster,burmanm/heapster,piosz/heapster,shilpamayanna/heapster,adfin/statster,Stackdriver/heapster,titilambert/heapster,huangyuqi/heapster,aegixx/heapster,johanneswuerbach/heapster,luxas/heapster,mwringe/heapster,piosz/heapster,AlmogBaku/heapster,liubog2008/heapster,mwringe/heapster,bruceauyeung/heapster,krzyzacy/heapster