Change file link in CSV templates to avoid errors in import.

#6078 

Original issue is about a broken link in the CSV file for a blog template. Here we change the link for files in other content types too.

For the blog type now there's no error:
![selection_184](https://cloud.githubusercontent.com/assets/4497748/3023636/2b704e70-dfea-11e3-8e59-c9b1f620eef7.png)

And the file in the CSV is in the blog post:
![selection_185](https://cloud.githubusercontent.com/assets/4497748/3023637/30a12a4a-dfea-11e3-90af-4202a71cdda5.png)