Add rollup stats to "sacctmgr stats"

$ sacctmgr show stats
Rollup statistics
	Hour       count:10     ave_time:103467 total_time:1034673      max_time:52360
	Day        count:0      ave_time:0      total_time:0            max_time:0
	Month      count:0      ave_time:0      total_time:0            max_time:0

... RPC stats by type and user