Revert "remove class based exercises"

This reverts commit 290e7f1da4.

leapYears/leapYears.js

@@ -1,8 +1,5 @@
-var leapYears = function(year) {
-  if (year % 4 !== 0 || (year % 100 == 0 && year % 400 != 0)) {
-    return false 
-  }
-  return true
+var leapYears = function() {
+
 }
 
 module.exports = leapYears

leapYears/leapYears.spec.js

@@ -4,19 +4,19 @@ describe('leapYears', function() {
   it('works with non century years', function() {
     expect(leapYears(1996)).toEqual(true);
   });
-  it('works with non century years', function() {
+  xit('works with non century years', function() {
     expect(leapYears(1997)).toEqual(false);
   });
-  it('works with ridiculously futuristic non century years', function() {
+  xit('works with ridiculously futuristic non century years', function() {
     expect(leapYears(34992)).toEqual(true);
   });
-  it('works with century years', function() {
+  xit('works with century years', function() {
     expect(leapYears(1900)).toEqual(false);
   });
-  it('works with century years', function() {
+  xit('works with century years', function() {
     expect(leapYears(1600)).toEqual(true);
   });
-  it('works with century years', function() {
+  xit('works with century years', function() {
     expect(leapYears(700)).toEqual(false);
   });
 });