Use https:// to check out libsass code

scripts/build.js

@@ -77,7 +77,7 @@ function initSubmodules(cb) {
   console.log('Detected a git install');
   console.log('Cloning libSass into src/libsass');
 
-  var clone = spawn('git', ['clone', 'git@github.com:sass/libsass.git', './src/libsass']);
+  var clone = spawn('git', ['clone', 'https://github.com/sass/libsass.git', './src/libsass']);
   manageProcess(clone, function(err) {
     if (err) {
       cb(err);