add ChangeLog to package

Signed-off-by: Sami Kerola <kerolasa@iki.fi>
add rpm spec file to contrib/

Signed-off-by: Sami Kerola <kerolasa@iki.fi>
relax build requirements

The requirements might be over the top relaxed now.  Well, we'll see if
someone ever complains.

Signed-off-by: Sami Kerola <kerolasa@iki.fi>