cubicweb #1832853 [i18n] internationalise according to recepient settings, not sender [open]

When someone uses a cubicweb in a different language that what I am using (eg. spanish) the notifications they create will be in their language. Cubicweb should be able to send me an email in english when a spanish speaking user generates a notification.

prioritynormal
typebug
done in<not specified>
load0.200
load left0.200
closed by<not specified>