django_markdown_static is not a valid tag library

I was just experimenting with your package for the first time—looks awesome!—and I ran into some trouble when I was trying to use the templatetags to render the javascript editors. Below is a screenshot of the error I was receiving. It looks like django 1.6 is having problems with [this line](https://github.com/klen/django_markdown/blob/develop/django_markdown/templatetags/django_markdown_static.py#L1). Any ideas for how to fix?

![screen shot 2014-12-10 at 2 53 14 pm](https://cloud.githubusercontent.com/assets/255672/5384094/74b2ae7e-807c-11e4-80f5-da800e1b6ae4.png)