[launcher] Implement new Launcher design for tiles

[Florian Boucault]

The differences in the single tiles betwee the Unity version in Natty and Unity-2D seems be the following:

- Different background color calculation.
- Gradient on the background color.
- Border around the tile (the color is one of those of the background gradient, need to check exactly this is calculated).
- Larger icon size.
- Icons for applications and files places, trash and workspaces have a new design.
- The icons mentioned above also have a different background than the regular application icons.
- The animation when an application is launched is different (the icon's background fades in and out)