Fixed that you are able to modify other peoples projects

Currently you are able to delete and publish/unpublish other projects if you only know the id. But you should only be allowed to update your own projects, so we need to filter the projects also by the `owner_id`.

By the way: The lfpr project needs to be republished on lookingforpullrequests.com because I unpublished for testing. (see http://www.lookingforpullrequests.com/project/2)