Any town, city or borough may, by ordinance, create a personnel appeals board which shall consist of five members who shall be electors of such municipality holding no salaried municipal office and whose term of office and method of election or appointment shall be fixed in the ordinance. Not more than three members shall be members of the same political party. The terms of office shall be arranged so that not more than one of such terms shall expire in any one year. Vacancies shall be filled for the unexpired portion of the term in the manner fixed in the ordinance. Three members shall constitute a quorum. Said board shall hear and determine any grievance, as defined in such ordinance, of any employee or group of employees of such town, city or borough. It shall adopt rules of procedures which shall insure any aggrieved employee a prompt and fair hearing and an opportunity to be heard in person or by a representative of his choosing. The decision of said board may be appealed to the Superior Court within ninety calendar days from the date such board renders its decision.