add report merging benchmark
add report merging benchmark

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