folder_block_manager: suggestions from @akalin-keybase
folder_block_manager: suggestions from @akalin-keybase

Issue: #768

keybase/client,keybase/kbfs,keybase/client,keybase/client,keybase/kbfs,keybase/client,keybase/client,keybase/kbfs,keybase/client,keybase/kbfs,keybase/client,keybase/client,keybase/client,keybase/client,keybase/client,keybase/client