We consider every contract to be a 'token holder' since it's currently not possible
for a contract to deny receiving tokens.
The TokenHolder's contract sole purpose is to provide a safety mechanism that allows
the owner to send tokens that were sent to the contract by mistake back to their sender.
Note that we use the non standard ERC-20 interface which has no return value for transfer
in order to support both non standard as well as standard token contracts.
withdraws tokens held by the contract and sends them to an account
can only be called by the owner
_token: ERC20 token contract address
_to: account to receive the new amount
_amount: amount to withdraw