Fix infinity scrolling 

I've recently started to use JMStatefulTableViewController 0.1.1 with SVPullToRefresh 0.4.1.
It seemed to me that issue  [#1](https://github.com/jakemarsh/JMStatefulTableViewController/issues/1) is still there. By digging code I realized that issue happens because after our callback in ```statefulTableViewControllerWillBeginLoadingNextPage:``` SVInfiniteScrollingView still has SVInfiniteScrollingStateLoading state and can't fire the handler. As mentioned in SVPullToRefresh docs you should manually call ```[tableView.infiniteScrollingView stopAnimating]``` inside infinity scrolling handler when you've done. It switches state to SVInfiniteScrollingStateStopped. I've added needed calls to ```_loadNextPage``` and it seems like everything works fine. 

I've also added ```initWithCoder:``` for correct initialization of my controllers which instantiated from storyboards.

Sorry if I'm wrong with something. Thanks.