Storage.store calls can be pipelined when implementation can take advantage of
it (as Zeo does). This allows reducing the impact of (network-induced, mainly)
latency by sending all objects to storages without waiting for storage answer.

git-svn-id: https://svn.erp5.org/repos/neo/trunk@1788 71dcc9de-d417-0410-9af5-da40c76e7ee4