Remove I18n.enforce_available_locales deprecation message

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>
Merge branch 'remove-annoying-i18n-deprecation' into 'master'

Remove annoying i18n deprecation

Thanks to this guy http://stackoverflow.com/a/20381730

Fixes #527

See merge request !197
Merge branch 'master' of gitlab.com:gitlab-org/gitlab-ce
Merge branch 'master' of github.com:gitlabhq/gitlabhq