Admin blocks translations not working

Hi,

I'm using Rubik as my default admin theme and as I'm not a native english speaker, my sites always have the locale module enabled.

While using Rubik I noticed that all titles for all blocks on admin/config page aren't getting the translation. I checked the code for Rubik and find out that the problem was with the wrong variable being used to get the block title on the preprocess function.

So here's a patch to solve this.

I hope it helps.