[Cin] Updated ru.po again, this time hopefully with Igor's email back!

Well, it took me *a lot of time* to figure out I should put main translator in "Language-Team" field, and then also in comments ... I looked at GIMP's po file [1] only today, after Igor contacted me and asked why his name/contribution was gone from po file. Hopefully _this time_ I did it right! (but of course I can tweak/fix it further) [1] - https://github.com/GNOME/gimp/blob/master/po/ru.po