The neighborhood is called Agritopia, and it’s one of a growing number of so-called agrihoods, residential developments where a working farm is the central feature, in the same way that other communities may cluster around a golf course, pool or fitness center. The real estate bust in 2008 halted new construction, but with the recovery, developers are again breaking ground on farm-focused tracts. At least a dozen projects across the country are thriving, enlisting thousands of home buyers who crave access to open space, verdant fields and fresh food.