Rather add UIControl+ALValidator category methods to UIView as UITextVie...

In the UIControl (ALPValidator) category, validators can be attached and removed on UIControls by using the methods ```removeValidators``` and ```attachValidator```.  However, the ```attachValidator``` method checks whether the object is a ```UITextView```:

```Objective-C
    NSArray *supported = @[
        [UITextField class],
        [UITextView class]
    ];
```

but ```UITextView``` extends ```UIScrollView``` and not ```UIControl```, which makes this functionality unusable on ```UITextView```. 

I've added the category to ```UIView```, but it might actually make more sense to make it more specific have them on ```UITextView``` and ```UITextField```. That way the methods aren't on all ```UIView``` objects.