Add partial for config of root password

tests/integration/manifests/__init__.py

@@ -12,4 +12,9 @@ for path in partial_json + partial_yaml:
 		msg = 'Error when loading partial manifests: The partial {key} exists twice'.format(key=key)
 		raise Exception(msg)
 	partials[key] = load_data(path)
-	
+
+import random
+import string
+pool = string.ascii_uppercase + string.ascii_lowercase + string.digits
+random_password = ''.join(random.choice(pool) for _ in range(16))
+partials['root_password']['plugins']['root_password']['password'] = random_password

tests/integration/manifests/root_password.yml

@@ -0,0 +1,4 @@
+---
+plugins:
+  root_password:
+    password: random password set by the partial manifest loader

tests/integration/virtualbox_tests.py

@@ -20,7 +20,8 @@ volume:
     type: msdos
 """)
 	manifest_data = tools.merge_dicts(partials['base'], partials['stable64'],
-	                                  partials['unpartitioned'], manifest_data)
+	                                  partials['unpartitioned'], partials['root_password'],
+	                                  manifest_data)
 
 	build_server = pick_build_server(build_servers, manifest_data)
 	manifest_data = build_server.apply_build_settings(manifest_data)