@dzucconi: Add slugs & more migration stuff

![image](https://cloud.githubusercontent.com/assets/555859/5080304/f5503ae0-6e8b-11e4-9a6b-c5cc8bd5bd25.png)

I should probably add some set of tests to the migration script... but I'm not sure what would be most useful. I'm thinking something crazy/high-level like using selenium to screenshot the output of a random sample of migrated posts would actually be more helpful than doing a traditional unit-testy thing.