Since request.LANGUAGE_CODE might not always be avialable use cms.utils.get_language_from_request

get_language_for_request has a fallback mechanism for django-cms setups that don't need any i18n features.
Merge pull request #2085 from pbs/fix-language-code

Since request.LANGUAGE_CODE might not always be avialable use cms.utils get_language_from_request