Corrects ageDifference.js

Author: JessRudder

ageDifference.js

@@ -1,8 +1,3 @@
-function average(array) {
-  function plus(a, b) { return a + b; }
-  return array.reduce(plus) / array.length;
-}
-
 var byName = {};
 ancestry.forEach(function(person) {
   byName[person.name] = person;