Update translation setup

Follow new infra setup for translations, see spec
http://specs.openstack.org/openstack-infra/infra-specs/specs/translation_setup.html
for full details.

This basically renames
oslo.messaging/locale/oslo.messaging.pot to
oslo_messaging/locale/oslo_messaging.pot. For this we need to update
setup.cfg.

Update also domain name in i18n.py.

Change-Id: Idf5300224f572d29953261ac998e7bf32a12822d

oslo_messaging/_i18n.py

@@ -19,7 +19,7 @@ See http://docs.openstack.org/developer/oslo.i18n/usage.html
 import oslo_i18n
 
 
-_translators = oslo_i18n.TranslatorFactory(domain='oslo.messaging')
+_translators = oslo_i18n.TranslatorFactory(domain='oslo_messaging')
 
 # The primary translation function using the well-known name "_"
 _ = _translators.primary

setup.cfg

@@ -70,18 +70,18 @@ all_files = 1
 upload-dir = doc/build/html
 
 [compile_catalog]
-directory = oslo.messaging/locale
-domain = oslo.messaging
+directory = oslo_messaging/locale
+domain = oslo_messaging
 
 [update_catalog]
-domain = oslo.messaging
-output_dir = oslo.messaging/locale
-input_file = oslo.messaging/locale/oslo.messaging.pot
+domain = oslo_messaging
+output_dir = oslo_messaging/locale
+input_file = oslo_messaging/locale/oslo_messaging.pot
 
 [extract_messages]
 keywords = _ gettext ngettext l_ lazy_gettext
 mapping_file = babel.cfg
-output_file = oslo.messaging/locale/oslo.messaging.pot
+output_file = oslo_messaging/locale/oslo_messaging.pot
 
 [pbr]
 warnerrors = true