These will allow clients to perform the minimal number of requests
required to accomplish some bulk tasks. For example, a client with
many objects to delete can learn that the cluster's limit on
deletes-per-request is, say, 128, and then batch up their deletes in
groups of 128. Without this, the client has to either discover the
limit out-of-band somehow (and get notified if it changes), or do some
sort of binary search to figure out the limit.
Similar reasoning applies to the containers-per-request value.
The errors-per-request values are included so that clients may size
their requests such that everything is attempted regardless of
failure.
I split the 'bulk' entry into 'bulk_delete' and 'bulk_upload' because,
from a client's standpoint, they're separate operations. It so happens
that Swift implements both in one piece of middleware, but clients
don't care.
Bonus fix: documented a missing config setting for the bulk middleware.
Change-Id: Ic3549aef79682fd5b798145c3545c1609aa1592b