distribute: Make server work with multiple remote disks

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

cmd/test-utils_test.go

@@ -888,7 +888,7 @@ func initTestAPIEndPoints(objLayer ObjectLayer, apiFunctions []string) http.Hand
 	// All object storage operations are registered as HTTP handlers on `objectAPIHandlers`.
 	// When the handlers get a HTTP request they use the underlyting ObjectLayer to perform operations.
 	api := objectAPIHandlers{
-		ObjectAPI: objLayer,
+		ObjectAPI: func() ObjectLayer { return objLayer },
 	}
 	// API Router.
 	apiRouter := muxRouter.NewRoute().PathPrefix("/").Subrouter()