Show StockArticle price details to user

- [x] Update `en` and `de` locales

Currently it is quite hard to find out e.g. the deposit of a `StockArticle`. This shall

* add the article price tooltip to the `StockTaking` form
* move the `StockArticle#history` to `StockArticle#show` where additional information are presented (I avoided to add the tooltip to the long `StockArticle#index` table. Let us care for the page loading speed.)

I am not sure how to handle the translations. Also see [my questions in foodcoops#137](https://github.com/foodcoops/foodsoft/issues/137#issuecomment-25658112). Some I could delete or rename on my own. Does this help? Now I plan to provide `en` and `de`. Would that be enough?