JOHNSTOWN — There really is an Uncle Bud, but he's not Karl Lakata's uncle and he's not in the same line of business.Lakata recently opened a horticulture shop on North Market Street and borrowed the nickname of the guy who would rent out a hay wagon for a music festival Lakata's friend organized."Bud" is also a nickname for marijuana, and that's what Lakata expects a lot of customers to be interested in as they visit Uncle Bud's Grow Shop. Growing your own marijuana at home will soon be a legal option in New York, and he expects a large demand for…