
Update worker proposal

Parameters:
    proposal_id: - the id of the proposal to update, (type: int64_t)
    creator: - the account that created the proposal, (type: const
	account_name_type &)
    daily_pay: - new amount of HBD to be requested to be paid out daily,
	(type: const wallet_serializer_wrapper<hive::protocol::asset> &)
    subject: - new description of the proposal, (type: string)
    permlink: - new permlink of the post for the proposal. (type: string)
    end_date: - new end_date of the proposal. (type:
	optional<time_point_sec>)
    broadcast: - true if you wish to broadcast the transaction (type: bool)
