Theming support for toolbars, removed some deprecation warnings

Hi, 

I have added support for controlling the light and dark color you use in the gradients of the three toolbars. Now you can set the theme colors once for your ReaderViewController and then the toolbars will have their colors set accordingly. 

Furthermore, I removed some deprecation warnings. It still compiles (without warnings) for iOS 5 but I have not tested iOS 4. I guess you don't really support iOS 4 anyway, right?

Thank you for open sourcing this great PDF viewer! 

Best regards, 
Mads