Getting list of followers
To get list of followers, change the URL
you are requesting to:
https://api.twitter.com/1.1/followers/list.json
It returns a cursored collection of user objects for users following the specified user.
Getting list of followed users
To get list of the users you follow, change the URL
you are requesting to:
https://api.twitter.com/1.1/friends/list.json
It returns a cursored collection of user objects for every user the specified user is following (otherwise known as their "friends").
I used your code to test it and it works. Based on REST API v1.1 Resources