Add support for secret files in credentials
Some refactoring:
 groovy code moved to separate template
 used common python module

Change-Id: Ic8e03cae92beeac80425515b7b5b6fd3a4e8aef0
diff --git a/README.rst b/README.rst
index 869ea5b..6b43e7e 100644
--- a/README.rst
+++ b/README.rst
@@ -585,6 +585,10 @@
             key: SOMESSHKEY
           cred_with_text_secret:
             secret: SOMETEXTSECRET
+          cred_with_secret_file:
+            filename: somefile.json
+            content: |
+              { "Hello": "world!" }
 
 Users enforcing from client: