fixed wrong call order in Ownable.transferOwnership

contracts/ownership/Ownable.sol

@@ -37,8 +37,8 @@ contract Ownable {
    */
   function transferOwnership(address newOwner) onlyOwner {
     require(newOwner != address(0));      
-    owner = newOwner;
     OwnershipTransferred(owner, newOwner);
+    owner = newOwner;
   }
 
 }