Any action required by the Business Corporation Act to be taken at a meeting of the shareholders of a corporation, or any action which may be taken at a meeting of the shareholders, may be taken without a meeting if a consent in writing, setting forth the action so taken, is signed by all of the shareholders entitled to vote with respect to the subject matter thereof. Such consent has the same effect as a unanimous vote of shareholders, and may be stated as such in any articles or document filed with the commission [secretary of state] under the Business Corporation Act.