Add basic application framework and example application to show interaction between events an NBI

Depends on:

• !340 (merged)
• !344 (merged)
• !349 (merged)
• !342 (merged)

controller/northbound/server/user.go

@@ -28,10 +28,11 @@ type User struct {
 	userService rbacInterfaces.UserService
 }
 
-// NewUserServer receives a JWTManager and returns a new UserServer.
-func NewUserServer(jwtManager *rbac.JWTManager) *User {
+// NewUserServer receives a JWTManager and a UserService and returns a new UserServer.
+func NewUserServer(jwtManager *rbac.JWTManager, userService rbacInterfaces.UserService) *User {
 	return &User{
-		jwtManager: jwtManager,
+		jwtManager:  jwtManager,
+		userService: userService,
 	}
 }