Adding this information AFTER being accused for plagiarism is the same as paying for something AFTER you got caught stealing it. Won't help!

Update: If you really didn't mean to put your name on somebody else's work, like you say, then see this as a learning. We are talking about Open Source software in the end, so using other people's work is actually what this here is all about. BUT it still has to be clear, which parts you took from another codebase. Simply copying the code from others and actually even removing all occurrences of the authors name is totally out of place. Furthermore, there are licenses that define what you can do with a software and what not. Even an Open Source license is still a license. At the time of writing your post, there actually wasn't any license at all in the original repository (@wehmoen's mistake actually). Strictly legally speaking you were not even allowed to use the software at all. Now there's a license. So feel free to use it within the given conditions. (Yes, this might be a bit fussy but we try to stick with the rules as good as possible.)