rfc: Hooks to help with cluster version upgrades
rfc: Hooks to help with cluster version upgrades

petermattis/cockroach,maxlang/cockroach,glycerine/cockroach,vaibhavarora/cockroach,petermattis/cockroach,glycerine/cockroach,vaibhavarora/cockroach,maxlang/cockroach,vaibhavarora/cockroach,paperstreet/cockroach,glycerine/cockroach,veteranlu/cockroach,vaibhavarora/cockroach,paperstreet/cockroach,maxlang/cockroach,maxlang/cockroach,maxlang/cockroach,veteranlu/cockroach,glycerine/cockroach,petermattis/cockroach,veteranlu/cockroach,glycerine/cockroach,paperstreet/cockroach,vaibhavarora/cockroach,paperstreet/cockroach,veteranlu/cockroach,glycerine/cockroach,veteranlu/cockroach,paperstreet/cockroach,paperstreet/cockroach,veteranlu/cockroach,petermattis/cockroach,glycerine/cockroach,maxlang/cockroach,vaibhavarora/cockroach,maxlang/cockroach,veteranlu/cockroach,petermattis/cockroach,glycerine/cockroach,paperstreet/cockroach,vaibhavarora/cockroach,maxlang/cockroach,vaibhavarora/cockroach,petermattis/cockroach,petermattis/cockroach,veteranlu/cockroach,petermattis/cockroach,paperstreet/cockroach