Scenario runner can print the the generated configuration

Print the generated YAML configuration when the verbose mode
is enabled.

Change-Id: Ia84f12fa3c833b4db84c4842e57083f074f381e9

releasenotes/notes/scenario-runner-templatesdebug-5ee5e2447cff770a.yaml

@@ -0,0 +1,4 @@
+---
+features:
+  - |
+    The fully generated YAML file is printed when the verbose mode is enabled.

sahara_tests/scenario/utils.py

@@ -125,6 +125,12 @@ def generate_config(files, template_variables, auth_values, verbose_run):
                 else:
                     raise ValueError('Job flow exist')
     config['credentials'].update(auth_values['credentials'])
+    if verbose_run:
+        six.print_("Generated configuration:\n%s" % (
+            yaml.safe_dump(config,
+                           allow_unicode=True,
+                           default_flow_style=False)),
+                   flush=True)
     return config