[c][p] Fix review comments

dfssc/cmd/unregister.go

@@ -25,13 +25,13 @@ var unregisterCmd = &cobra.Command{
 		var ready string
 		readStringParam("Do you REALLY want to delete "+cert.Subject.CommonName+"? Type 'yes' to confirm", "", &ready)
 		if ready != "yes" {
-			fmt.Println("Unregistering aborted!")
+			fmt.Fprintln(os.Stderr, "Unregistering aborted!")
 			os.Exit(1)
 		}
 
 		err = user.Unregister()
 		if err != nil {
-			fmt.Fprintln(os.Stderr, "Error: cannot unregister:", err.Error())
+			fmt.Fprintln(os.Stderr, "Cannot unregister:", err.Error())
 			os.Exit(2)
 		}
 	},

dfssp/user/delete.go

@@ -9,7 +9,7 @@ import (
 // Unregister delete a user based on the provided certificate hash
 func Unregister(manager *mgdb.MongoManager, userCertificateHash []byte) *api.ErrorCode {
 	count, err := manager.Get("users").DeleteAll(bson.M{
-		"certHash": bson.M{"$eq": userCertificateHash},
+		"certHash": userCertificateHash,
 	})
 	if err != nil || count == 0 {
 		return &api.ErrorCode{Code: api.ErrorCode_INVARG, Message: "No user matching provided certificate"}