Migrate translation scheme from file based to DB based

[bglusman]

Currently OpenPantry loads translations from files, but this will make allowing admins and volunteers who speak different languages and want to translate foods as needed for guests harder. We should replace current system with something managed in app, probably https://github.com/smeevil/ecto_translate but perhaps https://github.com/belaustegui/trans

Anyone picking this up will decide however they want which is better, they both look well supported and decent, welcome thoughts or reccomendations.