Fix for #563 Ember 3.0 compatability issue

Implemented backwards compat fix, rev 3

Fixes #563

Author: 0xadada

lib/build-utilities/migrate-initializers.js

@@ -89,10 +89,8 @@ function _moveFastBootInitializers(project, rootPath) {
  * @param {Object} project
  */
 function _migrateAddonInitializers(project) {
-  const nodeModulesPath = path.join(project.nodeModulesPath);
-
-  project.addons.forEach((addon) => {
-    const currentAddonPath = path.join(nodeModulesPath, addon.name);
+  project.addons.forEach(addon => {
+    const currentAddonPath = addon.root;
 
     _checkBrowserInitializers(currentAddonPath);
     _moveFastBootInitializers(project, currentAddonPath);