This change initializes rpc servers associated with disks that are
local. It makes object layer initialization on demand, namely on the
first request to the object layer.
Also adds lock RPC service vendorized minio/dsync
Current master has a regression 'mc policy <policy-type> alias/bucket/prefix'
does not work anymore, due to the way new minio-go changes do json marshalling.
This led to a regression on server side when a ``prefix`` is provided
policy is rejected as malformed from th server which is not the case with
AWS S3.
This patch uses the new ``minio-go/pkg/set`` package to address the
unmarshalling problems.
Fixes#2503
