Added ability to hide the drop shadow that appears during search

[sgtsquiggs]

This has some synergy with the existing pull request to hide the bottom border.

[davbeck]

Shouldn't this:

- (void)updateShadows
{
    if (_searching) {
        if (_showsShadows) {
            self.layer.shadowColor = [UIColor blackColor].CGColor;
            self.layer.shadowOffset = CGSizeMake(0.0, 0.0);
            self.layer.shadowOpacity = 0.5;
            self.layer.shadowRadius = 5.0;
            self.clipsToBounds = NO;
        }
    } else {
        if (_showsShadows) {
            self.layer.shadowOpacity = 0.0;
            self.layer.shadowRadius = 0.0;
            self.clipsToBounds = YES;
        }
    }
}

Be this?

- (void)updateShadows
{
    if (_searching && _showsShadows) {
        self.layer.shadowColor = [UIColor blackColor].CGColor;
        self.layer.shadowOffset = CGSizeMake(0.0, 0.0);
        self.layer.shadowOpacity = 0.5;
        self.layer.shadowRadius = 5.0;
        self.clipsToBounds = NO;
    } else {
        self.layer.shadowOpacity = 0.0;
        self.layer.shadowRadius = 0.0;
        self.clipsToBounds = YES;
    }
}

[sgtsquiggs]

Both work, the original just doesn't modify the layer/clipping at all if shadows are disabled. The revision is definitely cleaner.