feature/copy-vault-dataloader: Add method get_real_file(file_path) to dataloader

- get_real_file will decrypt vault encrypted files and return a path to
  a temporary file.

- cleanup_real_file will remove a temporary file created previously with
  get_real_file

test/integration/test_vault.yml

@@ -8,4 +8,6 @@
     - assert:
         that:
           - 'secret_var == "secret"'
+          
+    - copy: src=vault-secret.txt dest={{output_dir}}/secret.txt