The provisions of sections 78.310 to 78.390 shall apply to all appointive officers and employees of such city except those specially named in section 78.070, commissioners of any kind (laborers whose occupation requires no special skill or fitness), election officials and mayor’s secretary, and assistant attorney, where such officers are appointed; provided, however, that existing employees heretofore appointed or employed and who are performing their duties in a satisfactory manner may retain their positions without further examination, subject, however, to the approval of the council.