Factor out the dump-rewrite sed script since creating pretty-printed

xml fixtures in general is a useful thing to do.
 - Legacy-Id: 817

Author: fenner

ietf/bin/pretty-xml-dump

@@ -0,0 +1,5 @@
+#!/bin/sh
+python manage.py dumpdata --format=xml "$@" | sed -e 's/<\/*object/\
+  &/g' -e 's/<field/\
+    &/g' -e 's/<\/django-objects/\
+&/g'