Added visual properties

I added properties for all defines in PopoverView_configuration.h because I needed to display two popovers with different colors.

Values in PopoverView_configuration.h are still taken as defaults. Most of the properties needs to be set before you display popover and their changes wont affect displayed popover. If you want to customize PopoverView do not use static methods, use alloc init, then set required properties and then call one of the show methods. Or use UIAppearance.