Added EnderFacingEvent for when a player looks at an Enderman

This event is fired when a Player looks at an Enderman. This is useful
if you want to prevent an Enderman from going hostile against a Player
if he, for example, wears certain armor.

updated EnderFacingEvent class

It passes an EntityEnderman param in its constructor instead of an
EntityLiving one. Also added an EntityEnderman final field to prevent
unnecessary castings

removed unnecessary import in EnderFacingEvent class

Made event posting an one-liner

sqashed the code as suggested by LexManos.

Added EnderFacingEvent for when a player looks at an Enderman

This event is fired when a Player looks at an Enderman. This is useful
if you want to prevent an Enderman from going hostile against a Player
if he, for example, wears certain armor.