As used in this article, the term "contractor" means any person engaged in the business of constructing, altering, repairing, dismantling, or demolishing buildings, roads, bridges, viaducts, sewers, water and gas mains, streets, disposal plants, water filters, tanks and towers, airports, dams, water wells, pipelines, and every other type of structure, project, development, or improvement coming within the definition of real property or personal property including, but not limited to, constructing, altering, or repairing of property to be held either for sale or rental, and all subcontractors so engaged.