Implementation of Video Queue (show queue, add and remove entries)

I chose to create a resource under user to allow access to queues using routes that include the user ID.  But I also kept the my_queue route at root which is sent to the same controller.  The controller is tolerant of an omitted user_id and assumes it to mean the current logged in user.  Note that this complicated my test writing so I had to write extra tests for various cases of user_id supplied and omitted.

@user.video_queue_entries will return an empty array-like object if there are none. You should not need this if/else.

```ruby
@queue_entries = @user.video_queue_entries
```

That should be plenty, instead of the if/else.