Dragonfly doesn't send the player health and hunger on join

[mmm545]

Let's say your health was 16HP the last time you played, and you joined again, your health bar will appear full, but if you lose 2HP your health bar will actually show 14HP instead of 18HP.
It's caused by dragonfly not sending the health on join so it would appear full until you lose some health. This issue also occurs with hunger.

Steps to reproduce

1. Deal some damage (e.g 4HP)
2. Leave the server
3. Join again
4. Deal some damage again (e.g 2HP)
5. Your HP would be 14 instead of 18