Prevent accidental modification of statuses from outside class

At present unshifting additional statuses such as "Any" within a controller, will add them the the collection in the class variable. This pull request fixes this by returning a cloned collection.
![url](https://f.cloud.github.com/assets/259807/161340/954ca190-778b-11e2-9b7b-bcc220779f2f.jpeg)