tiny improvement: log container id in stats collection loop
tiny improvement: log container id in stats collection loop

alban/scope,kinvolk/scope,alban/scope,paulbellamy/scope,weaveworks/scope,kinvolk/scope,alban/scope,weaveworks/scope,weaveworks/scope,paulbellamy/scope,alban/scope,kinvolk/scope,weaveworks/scope,weaveworks/scope,kinvolk/scope,paulbellamy/scope,kinvolk/scope,alban/scope,kinvolk/scope,alban/scope,paulbellamy/scope,paulbellamy/scope,paulbellamy/scope,weaveworks/scope