Adds a button to delete the displayed translation of a blog post

A small addition allowing a user to delete a specific translation of a blog post by clicking a button next to the "remove" button.

If the blog post has only one translation then the remove translation button is not displayed.

I only added the EN/FR locales for the button, as I don't speak all the others :)

I was forced to use a CSS fix to be able to display this button next to the remove button. I think there is actually a CSS bug in the refinery gem but as I'm not sure I used this fix. (see the line annotation for more info).

Cheers !
we can use `&& @post.translations.many?` as well I think.