(overall facts and circumstances indicated that auto body shop workers, secretaries and shop trainee were employees and not independent contractors; petitioner retained right to control work and discharge at will and workers did not have home offices; petitioner should have withheld tax, and issued Forms W-2 and 1099-Misc; I.R.C. §520 safe harbor relief not available due to petitioner’s lack of filing any Forms 1099-Misc; additional workers properly classified as independent contractors).