Allow to use custom TypeHandlers for Enums

[MaxShoshin]

Try to deserialize enum via TypeHandler first (if exists)

Closes #259

[SimonCull]

Trying to remove my approval. I accidentally approved this pr and cannot seem to undo my approval. I'm not an expert on this code base and should not approve.

Can you put this in front of someone who can approve, this issue is 6 years old and the fix in simple enough.