Improve/safety

- Adds a new delegate:

```objc
- (void)dataSource:(ANDYFetchedResultsTableDataSource *)dataSource
     didMoveObject:(NSManagedObject *)object
     withIndexPath:(NSIndexPath *)indexPath newIndexPath:(NSIndexPath *)newIndexPath;
```

- Support hidden controllers:
```objc
@property (nonatomic) BOOL parentControllerIsHidden;
```

> If the controller is hidden it reloads contents without animations

- Refreshes cell contents when they get moved.
I've been thinking that they make sense at the top of the file, just like `- (instancetype)init`