add learn button back in and fix redirect loop associated with it

server/boot/challenge.js

@@ -101,7 +101,7 @@ module.exports = function(app) {
 
   const send200toNonUser = ifNoUserSend(true);
   const redirectNonUser = ifNoUserRedirectTo(
-    '/challenges/learn-how-free-code-camp-works'
+    '/map'
   );
 
   router.post(

server/views/partials/navbar.jade

@@ -7,6 +7,8 @@ nav.navbar.navbar-default.navbar-fixed-top.nav-height
             img.img-responsive.nav-logo(src='https://s3.amazonaws.com/freecodecamp/freecodecamp_logo.svg', alt='learn to code javascript at Free Code Camp logo')
     .collapse.navbar-collapse
         ul.nav.navbar-nav.navbar-right.hamburger-dropdown
+            li
+                a(href='/challenges') Learn
             li
                 a(href='/map') Map
             li