Fixing a few errors, adding support for attributedPlaceholder

so, the new textDidChange: method I have looks like this:

```
- (void)textDidChange:(NSNotification *)notification
{
    assert([notification.name isEqualToString:UITextFieldTextDidChangeNotification]);
    if (notification.object == self) {
        if ([self.text length]) {
            _storedText = [self text];
            if (![_floatLabel alpha]) {
                [self toggleFloatLabel:UIFloatLabelAnimationTypeShow];
            }
        } else {
            if ([_floatLabel alpha]) {
                [self toggleFloatLabel:UIFloatLabelAnimationTypeHide];
            }
        }
    }
}
```

I kept my conditionals, but wrapped them around your `notification.object` conditional check.