Add itBit and BitBay; Update Peru to shiny flag

[Mirobit]

I don't think exchanges that gamble with their customers money should be listed. That's why I removed Huobi and OkCoin.

I added itBit to us exchanges. Has been around for a while and is trusted.

[wbnns]

@Mirobit Hey, thanks for adding itBIt. Regarding removing the Chinese exchanges, I'm not sure we should remove them because:

1. AFAICS there has been no loss of customer funds.
2. Customers can withdrawal to any bitcoin address after using the exchange to convert fiat.
3. We have a bold disclaimer at the top of the page instructing users to choose a wallet where they will keep their bitcoin.
4. In the linked article, OKCoin says they do not use customer funds for their own gain and that the claim is false.

[Mirobit]

Okcoin and huobi have shown questionable behavior in the past and lied about it (e.g wash trading). We will only know if funds were lost when they collapse. I am afraid of an mtgox 2.0.

But I am fine with keeping this on hold till more evidence shows up.

[wbnns]

@Mirobit Ok, let's see. If you want to rebase and submit a separate PR to add itBit, that SGTM!

[Mirobit]

@wbnns I will open a new PR if the OkCoin/Huobi situation develops.

I also added the largest polish exchange.