Update CreateSubscription to API 1.1

https://dev.twitter.com/docs/api/1.1/post/lists/subscribers/create
Update DestroySubscription to API 1.1

https://dev.twitter.com/docs/api/1.1/post/lists/subscribers/destroy
Update GetSubscriptions to API 1.1

https://dev.twitter.com/docs/api/1.1/get/lists/subscriptions