Add unit test to check rendered models

Unit test implements simply yaml.load(..) to check the YAML
structure of the rendered model

- check rendered models based on 'inventory_examples' files
- generate context for rendering from {# interfaces #}
- generate context for rendering from {# roles #}

Change-Id: I535d3f0995ab84027b1b5ad0a9bc78b198626b03
diff --git "a/\173\173 cookiecutter._env_name \175\175/init.yml" "b/\173\173 cookiecutter._env_name \175\175/init.yml"
index f803888..b2d4978 100644
--- "a/\173\173 cookiecutter._env_name \175\175/init.yml"
+++ "b/\173\173 cookiecutter._env_name \175\175/init.yml"
@@ -1,9 +1,8 @@
-{# 'infra_config_classes' list object is dynamically generated from 'roles' to add on the cfg node #}
+{#- 'infra_config_classes' list object is dynamically generated from 'roles' to add on the cfg node #}
 {%- set infra_config_classes = [] %}
-{# 'global_metadata' is a global collection of objects shared between nodes #}
+{#- 'global_metadata' is a global collection of objects shared between nodes #}
 {%- set global_metadata = {} %}
 {%- set common_roles = ['_linux_network_interface', '_metadata_process', '_overrides'] %}
-
 parameters:
   _param:
     _esc: $