Loggin using MDCLogger

This commit includes:
* Enabled logging using MDCLogger.
* Test case updates.
* Addition of go.sum.

Issue-ID: RIC-831
Change-Id: I4d9fb56acd7f0c5d0bd4f4ae79c851a2d6735e6c
Signed-off-by: subhash kumar singh <subh.singh@samsung.com>
diff --git a/a1-go/cmd/a1.go b/a1-go/cmd/a1.go
index 097b0d9..2ec0d7b 100644
--- a/a1-go/cmd/a1.go
+++ b/a1-go/cmd/a1.go
@@ -21,6 +21,7 @@
 package main
 
 import (
+       "gerrit.o-ran-sc.org/r/ric-plt/a1/pkg/a1"
        "gerrit.o-ran-sc.org/r/ric-plt/a1/pkg/restful"
 )
 
@@ -33,5 +34,7 @@
 
 	// start restful service to handle a1 api's
 	restful := restful.NewRestful()
+
+       a1.Logger.Info("Starting a1 mediator.")
 	restful.Run()
 }