Add owners file coverage for fetch_artifact

BUG=121042212

Change-Id: Ie8fa57ed19ed65cd066450bb862099aa0282e43d
diff --git a/OWNERS b/OWNERS
new file mode 100644
index 0000000..675cfa1
--- /dev/null
+++ b/OWNERS
@@ -0,0 +1,2 @@
+samccone@google.com
+napier@google.com