Add package-source.sh helper

Automates creating a source tarball with the right
folder name inside

package-source.sh

@@ -0,0 +1,11 @@
+#!/bin/bash -eux
+
+# Get git version, something like "v1.2.3"
+GITVERSION=$(git describe --tags --dirty)
+# Drop leading "v" to get just "1.2.3"
+VERSION=${GITVERSION#v}
+# Folder name inside the tarball should be "encfs-1.2.3"
+PREFIX="encfs-$VERSION"
+
+# Actually create archive
+git archive --prefix "$PREFIX/" -o $PREFIX.tar.gz HEAD