Fix install failure when busybox can't be downloaded

Whether or not the "busybox" image downloads and runs properly at the end of the build, we don't want to have the script return a failing exit code, especially since at that point, Docker is successfully installed, and we're just tooting our own horn for good measure.

hack/install.sh

@@ -116,7 +116,7 @@ case "$lsb_dist" in
 			(
 				set -x
 				$sh_c 'docker run busybox echo "Docker has been successfully installed!"'
-			)
+			) || true
 		fi
 		exit 0
 		;;