Downtown Easton is going to the dogs. Hot dogs, specifically. A long-vacant space on Northampton Street has found a tenant, as a new specialty hot dog spot is setting up shop. Bun Busterz Gourmet Dogs is moving into 235 Northampton St. just east of Centre Square, a space last filled by Joe’s Delicatessen. Co-owner Jose Pinargote said in an email that the new fast-casual eatery is targeting a May opening.