Don't crash if docker API is disabled by params
Don't crash if docker API is disabled by params

weaveworks/weave,n054/weave,paulbellamy/weave,paulbellamy/weave,n054/weave,n054/weave,n054/weave,weaveworks/weave,weaveworks/weave,n054/weave,paulbellamy/weave,weaveworks/weave,paulbellamy/weave