Update the Wallet.sol to include new updated code

[alexvandesande]

I'm putting this here as an reminder of an important task

We have a new wallet proposed by @bencxr that we'll wait to be PRd into the app-bin repository. We need to watch these changes:

https://github.com/ethereum/dapp-bin/blob/master/wallet/wallet.sol
ethereum/dapp-bin#62
https://github.com/BitGo/eth-multisig-v2/blob/master/contracts/Wallet.sol

[taoteh1221]

Has this ERC20 multisig compatibility been added yet to current Mist / Ethereum Wallet versions? Curious if ERC20 tokens can be multisig-secured through this GUI yet.