Corrected sprintf format in Norwegian translation for users/index.html.erb

The page failed with this error: invalid value for Integer(): "aktiv"

By the way, am I stepping on anybody's toes if I suggest some changes to the Norwegian translation? Does anyone have specific responsibility for that?

::tor

(Disclaimer: Not experienced in Ruby, Rails, or Typo. I am however experienced in programming and debugging serverside scripted web pages.)