With this commit, each storage policy can define the diskfile to use to
access objects. Selection of the diskfile is done in swift.conf.
Example:
[storage-policy:0]
name = gold
policy_type = replication
default = yes
diskfile = egg:swift#replication.fs
The diskfile configuration item accepts the same format than middlewares
declaration: [[scheme:]egg_name#]entry_point
The egg_name is optional and default to "swift". The scheme is optional
and default to the only valid value "egg". The upstream entry points are
"replication.fs" and "erasure_coding.fs".
Co-Authored-By: Alexandre Lécuyer <alexandre.lecuyer@corp.ovh.com>
Co-Authored-By: Alistair Coles <alistairncoles@gmail.com>
Change-Id: I070c21bc1eaf1c71ac0652cec9e813cadcc14851