Bug 10802: make Debian package install history.txt

Bug 10802: make Debian package install history.txt

While bug 8911 fixed a problem regarding history.txt, a proper fix for
packages was missing.
This patch does three things:

 - Adds docs/history.txt to debian/koha-common.docs so it gets installed.
 - Moves the line installing the release notes from debian/koha-common.install
   to debian/koha-common.docs.
 - Adds an override_dh_compress entry in debian/rules that excludes
   history.txt from the dh_compress routine [1]

To test:
 - Take a picture of how /usr/share/doc/koha-common looks.
 - Apply the patch and build a package.
 - Upgrade and/or install using your package.
 - Look for the contents of the /usr/share/doc/koha-common, it should
   look the same, but history.txt must be there.
 - More > About Koha > Koha Timeline should show the history lines.

[1] As 'man dh_compress' says, it is needed as every file considered for
    the doc dir that is plain text and is more than 4k size will be
    gzipped unless stated otherwise. We need it uncompressed for about.pl.

Sponsored-by: Universidad Nacional de Cordoba
Signed-off-by: Chris Cormack <chris@bigballofwax.co.nz>
Signed-off-by: Mason James <mtj@kohaaloha.com>
Signed-off-by: Galen Charlton <gmc@esilibrary.com>