Merge pull request #4399 from ipfs/gx/datastore-1.4.0

blocks/blockstore/arc_cache.go

blocks/blockstore/arc_cache_test.go

blocks/blockstore/blockstore.go

blocks/blockstore/blockstore_test.go

blocks/blockstore/bloom_cache_test.go

blocks/blockstore/util/remove.go

blockservice/blockservice_test.go

blockservice/test/blocks_test.go

core/builder.go

core/commands/dht.go

core/core.go

core/coreunix/add.go

core/coreunix/metadata_test.go

exchange/bitswap/decision/engine_test.go

exchange/bitswap/testnet/peernet.go

exchange/bitswap/testutils.go

exchange/offline/offline_test.go

exchange/reprovide/reprovide_test.go

filestore/filestore.go

filestore/filestore_test.go