cli: allow setting --key with env var COCKROACH_KEY.
cli: allow setting --key with env var COCKROACH_KEY.

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