mongodb: hardcode service.name to avoid "/" (#821)
mongodb: hardcode service.name to avoid "/" (#821)

https://mesosphere.atlassian.net/browse/DCOS-11294
ksivask/universe,mesosphere/universe,aloismayr/universe,ksivask/universe,niteshch207/universe,BuoyantIO/universe,yuchaoran2011/universe,yuchaoran2011/universe,ksivask/universe,BuoyantIO/universe,mesosphere/universe,AppliedIS/universe,AppliedIS/universe,madanadit/universe,dbtucker/universe,BuoyantIO/universe,aloismayr/universe,niteshch207/universe,mwl/universe,dbtucker/universe,dbtucker/universe,AppliedIS/universe,madanadit/universe,madanadit/universe,mwl/universe,yuchaoran2011/universe,niteshch207/universe,aloismayr/universe