userpage: use form langfile, move login strings to common

login-related stuff was moved into common using the langmover script, so
that the user page doesn't have to use the admin language files.

lang/email/sv-se.json

@@ -62,4 +62,4 @@
         "yourAccountHasExpired": "Ditt konto har gått ut.",
         "contactTheAdmin": "Kontakta administratören för mer information."
     }
-}
+}