Issue on WP8 devices and desktop regarding focus; issue with focus when useClick is enabled

Added support due to focus issues on desktop and WP8 devices. On WP8 devices, touching a menu would cause it to only show while focus is set, and scrolling was blocked. Added check to prevent touch scroll blocking when "useClick" is enabled. This allows the device scrolling to work on WP8 when "useClick" is enabled.

the focushandler also helps to fix an issue on desktop when "useClick" is enabled. When a menu is clicked and shown, switching tabs in the browser and then coming back would cause the focus to re-trigger the "show" animation. Now, if a click triggers the display focus is not set which prevents the end from firing when focus on the window is changed.