The general manager of a business in El Cajon is being charged with immigration and employment fraud. John Washburn, the general manager of San Diego Powder & Protective Coatings, is being charged with conspiracy to harbor aliens. Washburn and three employees were arrested Thursday during a raid of the business, with the other three men charged with using false documents to work in the United States. The general manager is accused of employing undocumented workers and allowing them to live in the company’s warehouse…