Update ci-perf-kit to plot epoch (#1208) #128

Job	Run time
get-merged-pr	2s
binding-refs / binding-refs	2s
check-merge-julia-pr / process-pr	1s
check-merge-jikesrvm-pr / process-pr	7s
check-merge-ruby-pr / process-pr	3s
check-merge-openjdk-pr / process-pr	3s
check-merge-v8-pr / process-pr	2s
	20s

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