Auto color fix

With my fix, the result color of the navigation bar will be exactly the color passed into `- (void)setBarTintColor:(UIColor *)barTintColor` (saying on white background)

And I've also changed preset colors:

Red: to the color from [NetEase News App (Chinese)](http://itunes.apple.com/us/app/wang-yi-xin-wen/id425349261)
Green: to the color from [my new app](https://itunes.apple.com/us/app/id722318776?mt=8) which is in green
Blue: to the color from [Facebook](https://itunes.apple.com/us/app/facebook/id284882215)