Adopt dsync interface changes and major cleanup on RPC server/client.

* Rename GenericArgs to AuthRPCArgs
* Rename GenericReply to AuthRPCReply
* Remove authConfig.loginMethod and add authConfig.ServiceName
* Rename loginServer to AuthRPCServer
* Rename RPCLoginArgs to LoginRPCArgs
* Rename RPCLoginReply to LoginRPCReply
* Version and RequestTime are added to LoginRPCArgs and verified by
  server side, not client side.
* Fix data race in lockMaintainence loop.

cmd/test-utils_test.go

@@ -56,9 +56,11 @@ import (
 
 // Tests should initNSLock only once.
 func init() {
+	// Set as non-distributed.
+	globalIsDistXL = false
+
 	// Initialize name space lock.
-	isDist := false
-	initNSLock(isDist)
+	initNSLock(globalIsDistXL)
 
 	// Disable printing console messages during tests.
 	color.Output = ioutil.Discard
@@ -426,9 +428,6 @@ func StartTestPeersRPCServer(t TestErrHandler, instanceType string) TestServer {
 	// Run TestServer.
 	testRPCServer.Server = httptest.NewServer(mux)
 
-	// Set as non-distributed.
-	globalIsDistXL = false
-
 	// initialize remainder of serverCmdConfig
 	testRPCServer.SrvCmdCfg = srvCfg