[C] Make setTamed behave the same as vanilla taming. Fixes BUKKIT-3992

#### The Issue:
Using setTamed right now only sets the tame flag, it doesn't properly update health or anything else.

#### Justification for this PR:
Setting an entity as tamed via Bukkit should have the same effect as taming them in vanilla.

#### PR Breakdown:
This PR alters the setTamed method to trigger all the same flags and checks as when taming occurs in vanilla.

#### JIRA Ticket:
BUKKIT-3992 - https://bukkit.atlassian.net/browse/BUKKIT-3992