Status and nav bar customization (1/2)

- Status bar transparency
- Status bar colors
- Status bar transparency mode
- Nav bar (enable/disable)
- Nav bar dimensions (height, height in landscape and width)
- Nav bar background (color, transparency and transparency mode)
- Several changes in SystemSettings.java, by me, to enable navigation bar in devices with hardware buttons and also show all expanded desktop options
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Change-Id: I76aa83b0c6977e0a5404409ed5fba4c9b80d8728