Use gzip compression in Ubuntu packages to make it at least possible to install on Lucid.

Docker-DCO-1.1-Signed-off-by: Evan Krall <krall@yelp.com> (github: EvanKrall)
Upstream-commit: c2a59dfe48e55bc93e3bed5ecde021f372151b09
Component: engine

components/engine/hack/make/ubuntu

@@ -123,7 +123,7 @@ EOF
 		    --config-files /etc/init/docker.conf \
 		    --config-files /etc/init.d/docker \
 		    --config-files /etc/default/docker \
-		    --deb-compression xz \
+		    --deb-compression gz \
 		    -t deb .
 		mkdir empty
 		fpm -s dir -C empty \
@@ -134,7 +134,7 @@ EOF
 		    --maintainer "$PACKAGE_MAINTAINER" \
 		    --url "$PACKAGE_URL" \
 		    --license "$PACKAGE_LICENSE" \
-		    --deb-compression xz \
+		    --deb-compression gz \
 		    -t deb .
 	)
 }