Changes to integer-gmp

Changes to integer-gmp:
commit 747a360bf09b6c3c851ac6c884ee769180a71db7
Author: Herbert Valerio Riedel <hvr@gnu.org>
Date:   Sat Feb 1 11:46:33 2014 +0100

    Add Hackage-supported `changelog.md`

    Signed-off-by: Herbert Valerio Riedel <hvr@gnu.org>