add script to create tarball from tag

Signed-off-by: Stephan Raue <stephan@openelec.tv>

diff --git a/create_tar.sh b/create_tar.sh
new file mode 100755 (executable)
index 0000000..2153c43
--- /dev/null
+++ b/create_tar.sh
@@ -0,0 +1,3 @@
+#!/bin/sh
+
+git archive --format=tar --prefix=dvb-firmware-$1/ tags/$1 | xz > dvb-firmware-$1.tar.xz