Allow '.yml'/'.yaml' extension on group_vars files.

Look for a file with the base name of the group/host, first without
a file extension, then with a '.yml' extension, and, finally, with
a '.yaml' extension, loading vars from only the first one found.

lib/ansible/inventory/vars_plugins/group_vars.py

@@ -44,7 +44,9 @@ class VarsModule(object):
 
         # load vars in inventory_dir/group_vars/name_of_group
         for x in groups:
-            path = os.path.join(basedir, "group_vars/%s" % x)
+            p = os.path.join(basedir, "group_vars/%s" % x)
+            paths = [p, '.'.join([p, 'yml']), '.'.join([p, 'yaml'])]
+            for path in paths:
                 if os.path.exists(path):
                     data = utils.parse_yaml_from_file(path)
                     if type(data) != dict:
@@ -54,9 +56,12 @@ class VarsModule(object):
                         results = utils.merge_hash(results, data)
                     else:
                         results.update(data)
+                    break
 
         # load vars in inventory_dir/hosts_vars/name_of_host
-        path = os.path.join(basedir, "host_vars/%s" % host.name)
+        p = os.path.join(basedir, "host_vars/%s" % host.name)
+        paths = [p, '.'.join([p, 'yml']), '.'.join([p, 'yaml'])]
+        for path in paths:
             if os.path.exists(path):
                 data = utils.parse_yaml_from_file(path)
                 if type(data) != dict:
@@ -66,5 +71,6 @@ class VarsModule(object):
                     results = utils.merge_hash(results, data)
                 else:
                     results.update(data)
+                break
         return results