Fixes internacionalization issues

This pull request fixes the removal of auto search for `locale` dir on Django 1.5. This feature was deprecated since 1.3 and was removed on 1.5. So, when the Django version changed, the translation broke. To see more details about this issue, you can read about the [LOCALE_PATH settings](https://docs.djangoproject.com/en/1.5/ref/settings/#std:setting-LOCALE_PATHS) and [how Django discover transations](https://docs.djangoproject.com/en/1.5/topics/i18n/translation/#how-django-discovers-translations) on the 1.5 version.

Seizing the opportunity, I updated Django version to 1.5.1 that fixes an issue with a possible memory leak. See the [release blog post](https://www.djangoproject.com/weblog/2013/mar/28/django-151/) for more info.