Fixes small bugs

+ With MDNLinks and bonfireExecute being run on step challenges.
+ Return when common isn't loaded in reBindModals instead of throwing.

client/main.js

@@ -252,7 +252,7 @@ $(document).ready(function() {
 
   function reBindModals() {
     if (!window.common) {
-      throw new Error('common framework should be loaded.');
+      return;
     }
     var common = window.common;
 

server/views/coursewares/showBonfire.jade

@@ -135,6 +135,6 @@ block content
         }
       });
 
-      if (!{JSON.stringify(MDNlinks.length)}) {
+      if (!!{JSON.stringify(MDNlinks.length)}) {
           $('#MDN-links').addClass('collapse');
       }

server/views/coursewares/showJS.jade

@@ -101,7 +101,7 @@ block content
 
     include ../partials/challenge-footer
     script.
-      if (!{JSON.stringify(MDNlinks.length)}) {
+      if (!!{JSON.stringify(MDNlinks.length)}) {
           $('#MDN-links').addClass('collapse');
       }
       document.addEventListener('gitter-sidecar-ready', function(e) {

server/views/coursewares/showStep.jade

@@ -39,7 +39,7 @@ block content
 
       common.challengeId = !{JSON.stringify(challengeId)};
       common.challengeName = !{JSON.stringify(name)};
-      common.challengeType = 7;
+      common.challengeType = !{JSON.stringify(challengeType)};
       common.dashedName = !{JSON.stringify(dashedName || '')};
       common.isHonest = !{JSON.stringify(isHonest || false)};
       common.isFrontEndCert = !{JSON.stringify(isFrontEndCert || false)};