* FIX: Do not encode the URL twice
Now that we encode slugs in the server we don't need this anymore.
Reverts fe5na33
* FIX: More places do deal with encoded slugs
* the param is a string now, not a hash
* FIX: Handle the nil slug on /categories
* DEV: Add seeded? method to identity default categories
* DEV: Use SiteSetting to keep track of seeded categories