Merge 'master' branch

app/observers/users_project_observer.rb

@@ -3,4 +3,20 @@ class UsersProjectObserver < ActiveRecord::Observer
     return if users_project.destroyed?
     Notify.project_access_granted_email(users_project.id).deliver
   end
+
+  def after_create(users_project)
+    Event.create(
+      project_id: users_project.project.id,
+      action: Event::Joined,
+      author_id: users_project.user.id
+    )
+  end
+
+  def after_destroy(users_project)
+    Event.create(
+      project_id: users_project.project.id, 
+      action: Event::Left, 
+      author_id: users_project.user.id
+    )
+  end
 end