Undo some damage done by wget or similar

This was note caused by the initial import, it is from upstream.
Add missing cover.html

http://history.nasa.gov/SP-4205/cover.html
Restore the next/previous/index images

Source:

http://web.archive.org/web/20000229092815/http://www.dfrc.nasa.gov/GIF/next.gif
http://web.archive.org/web/20000229100217/http://www.dfrc.nasa.gov/GIF/previous.gif
http://web.archive.org/web/20000428233545/http://www.dfrc.nasa.gov/GIF/index.gif