Zone-entry permissions

Currently depends on https://github.com/ForgeEssentials/ForgeEssentialsMain/pull/1126 but can easily be changed to use old WarpPoint.

This PR implements permissions to deny players from entering zones by applying different effects (knockback, damage, potion, command).
**It is especially intended for use in plots.**
The current permissions are 
````
fe.wb.command         # Execute this command if a player enters the area
fe.wb.damage          # Apply this amount of damage to players, if they are in this area
fe.wb.damage.timeout  # Time interval in milliseconds for applying damage-effect
fe.wb.knockback       # Deny players from entering this area by kicking them out of it
fe.wb.potion          # Apply potion effects to players who enter this area. Comma separated list of "ID:duration:amplifier" values. See http://www.minecraftwiki.net/wiki/Potion_effects#Parameters
fe.wb.potion.timeout  # Time interval in milliseconds for applying potion-effects
````

This is not intended for merging yet and more like a draft, but it already works.
Suggestions for improvement needed.
It's just the event factory for PlayerChangedZone which has been moved from ForgeEssentialsEventFactory, because zones are part of permissions.