CORD-1954 move header.py and add symlink

Change-Id: I749fc58d572365d6de090d8ac02abc3605dc28b2
(cherry picked from commit f90d39d1efc5560d83b1cbfa4234d52e7e001989)
diff --git a/xos/header.py b/xos/attic/header.py
similarity index 100%
rename from xos/header.py
rename to xos/attic/header.py
diff --git a/xos/header.py b/xos/header.py
new file mode 120000
index 0000000..721b5c0
--- /dev/null
+++ b/xos/header.py
@@ -0,0 +1 @@
+attic/header.py
\ No newline at end of file