Negative values have no sense. On the other hand it differs from the
blobovnicza's configuration and prevents unification.
Signed-off-by: Pavel Karpy <carpawell@nspcc.ru>
1. Move compression parameters to the `shard` section.
2. Allow to use multiple sub-storage components in the blobstor.
Signed-off-by: Evgenii Stratonikov <evgeniy@nspcc.ru>
