- Remove 1900x1200 background image
- Fix permission of some images (should be 0644)

Older versions of plymouth used to clear the screen if the display
resolution changed whilst the splash screen was being displayed. The
current version leaves the old image in place, thus either partially
filling the screen or being cropped, depending on whether the display
resolution went up or down. We can use the display hotplug callback
mechanism to detect when the display reolution changes and resize the
image accordingly.

Add CREDITS for screensavers