Removed entire __new__() method

`SteamUser` no longer inherits from `int`, and is therefor redundant.

steam/client/user.py

@@ -13,9 +13,6 @@ class SteamUser(object):
     steam_id = SteamID()
     relationship = EFriendRelationship.No   #: friendship status
 
-    def __new__(cls, steam_id, *args, **kwargs):
-        return super(SteamUser, cls).__new__(cls) # removed "steam_id" arg from __new__()
-
     def __init__(self, steam_id, steam):
         self._pstate_ready = Event()
         self._steam = steam