Multisigwallet for erc20

[jeddie-yhc]

We have found a way to integrate MultiSigWallet with ERC20Token (which means to transfer any ERC20 Token through this contract, we will need to do MultiSig first.)

We have modified the followings in the codes:

1. Add ERC20Token Interface
2. Update Transaction struct
3. Change the arguments of the functions
   i. submitTransaction(address contract_address, address send_to, uint value, bytes data)
   ii. addTransaction(address contract_address, address send_to, uint value, bytes data)
4. Use transfer to executeTransaction

   ERC20Token erc20token = ERC20Token(txn.contract_address);
   if (erc20token.transfer(txn.send_to, txn.value)) ...