ESLint: Accept "eslintRulePaths" from outside

Author: Turbo87

lib/ember-build.js

@@ -234,7 +234,7 @@ var EmberBuild = CoreObject.extend({
         htmlbars: this.htmlbars,
         glimmer: this.glimmer,
         vendoredPackages: vendoredPackages,
-        eslintRulePaths: ['lib/eslint-rules'],
+        eslintRulePaths: this.eslintRulePaths,
       });
 
       if (currentPackage['vendorRequirements']) {