Moved "About" menu item to the bottom of menu.

Reason: "About" are usually last items in menus.
[N9] Added support for toggling inverted style on Harmattan.

Some UI elements and icons need to be tweaked to take style into account.
[N9] Updated all UI elements, except icons, to follow inverted style.
[N9] Updated all icons to follow inverted style.
[N9] Removed unused icon.
Merge pull request #50 from leppa/inverted-harmattan

Inverted style on Harmattan