updating admin link in view to "admin/article"

The admin link by default is set to "http://.../admin". However, after installing the app I get an NotFoundHttpException, cause the routing is pointing to "http://.../admin/article/..."

This small change, fixes the links/application to work right out of the box.
Merge pull request #20 from dezwald/patch-1

Updating admin link in view to "admin/article"