carbon: add more counters and do background ops every 50s
carbon: add more counters and do background ops every 50s

50s to make sure that we do it at least once per minute.

iksaif/biggraphite,Thib17/biggraphite,iksaif/biggraphite,criteo/biggraphite,Thib17/biggraphite,Thib17/biggraphite,dpanth3r/biggraphite,criteo/biggraphite,criteo/biggraphite,iksaif/biggraphite,criteo/biggraphite,Thib17/biggraphite,iksaif/biggraphite