Add inital i18n translation support

The filter_plugin translate allows to translate strings using yavdr.mo
files from the package yavdr-i18n.

ansible-playbook must be called with an UTF-8 locale (e.g. de_DE.UTF-8), LANG=C or
LANG=POSIX are not allowed.

Usage of the new filter:

"{{ "my string" | translate }}"

filter_plugins/translate_yavdr.py

@@ -12,23 +12,18 @@
     'supported_by': 'yavdr'
 }
 
-
+import gettext
 from ansible.errors import AnsibleFilterError
-from ansible.module_utils.six.moves.urllib.parse import urlsplit
-from ansible.module_utils._text import to_text
 from ansible.utils import helpers
 
 
-def translate_yavdr(text, language=None, **kwargs):
-    if language is None:
-        language = kwargs.get('system_language', 'en')
-    translation = kwargs.get('translations', {}).get(language, {}).get(text, None)
-    if translation:
-        return translation
-    else:
+def translate_yavdr(text):
+    gettext.textdomain('yavdr')
+    try:
+        return gettext.gettext(text)
+    except:
         return text
 
-
 # ---- Ansible filters ----
 class FilterModule(object):
     ''' URI filter '''

group_vars/all

@@ -1,6 +1,9 @@
 ---
 # file: group_vars/all
 
+# for translation filter
+locale: "{{ ansible_env.LANG }}"
+
 # this is the standard text to put in templates
 ansible_managed_file: "*** YAVDR: ANSIBLE MANAGED FILE ***"
 branch: experimental