Install changelog.gz and Makefile fix

Tested.
Proof:

[15:29:02]abalashov@abalashow-ws:~/Dropbox/develop/curseofwar/repo/curseofwar $ sudo rm -rf /tmp/curs/

[15:29:33]abalashov@abalashow-ws:~/Dropbox/develop/curseofwar/repo/curseofwar $ sudo make DESTDIR=/tmp/curs/ install
install -m 755 -D curseofwar /tmp/curs//usr/bin/curseofwar
install -m 775 -d /tmp/curs//usr/share/man/man6
sed "s/%VERSION%/`cat VERSION`/g" curseofwar.6 | gzip -c > /tmp/curs//usr/share/man/man6/curseofwar.6.gz
install -m 755 -d /tmp/curs//usr/share/doc/curseofwar
cat CHANGELOG | gzip -c > /tmp/curs//usr/share/doc/curseofwar/changelog.gz
chmod 644 /tmp/curs//usr/share/man/man6/curseofwar.6.gz

[15:29:45]abalashov@abalashow-ws:~/Dropbox/develop/curseofwar/repo/curseofwar $ tree /tmp/curs/
/tmp/curs/
└── usr
    ├── bin
    │   └── curseofwar
    └── share
        ├── doc
        │   └── curseofwar
        │       └── changelog.gz
        └── man
            └── man6
                └── curseofwar.6.gz

7 directories, 3 files

[15:29:49]abalashov@abalashow-ws:~/Dropbox/develop/curseofwar/repo/curseofwar $ sudo rm -rf /tmp/curs/

[15:29:57]abalashov@abalashow-ws:~/Dropbox/develop/curseofwar/repo/curseofwar $ sudo make PREFIX=/tmp/curs/ install
install -m 755 -D curseofwar /tmp/curs//bin/curseofwar
install -m 775 -d /tmp/curs//share/man/man6
sed "s/%VERSION%/`cat VERSION`/g" curseofwar.6 | gzip -c > /tmp/curs//share/man/man6/curseofwar.6.gz
install -m 755 -d /tmp/curs//share/doc/curseofwar
cat CHANGELOG | gzip -c > /tmp/curs//share/doc/curseofwar/changelog.gz
chmod 644 /tmp/curs//share/man/man6/curseofwar.6.gz

[15:30:00]abalashov@abalashow-ws:~/Dropbox/develop/curseofwar/repo/curseofwar $ tree /tmp/curs/
/tmp/curs/
├── bin
│   └── curseofwar
└── share
    ├── doc
    │   └── curseofwar
    │       └── changelog.gz
    └── man
        └── man6
            └── curseofwar.6.gz

6 directories, 3 files