Handle count option

I want to use gettext_i18n_rails with db repository to completely replace I18n.

But when it comes to some rails helper methods such as time_ago_in_words, things do not work as expected.

Behind the scene, rails uses something like I18n.t("datetime.distance_in_words.about_x_hours", :count => 1) to translate the time. However, gettext_i18n_rails does not handle count option, which make the translation impossible

The idea is to call the plural translation when the count option is given.