Honolulu Mayor Kirk Caldwell on Tuesday signed into law a bill that provides incentives to owners of small parcels of land in apartment- and business-mixed-use-zoned areas for building walk-up rental buildings for tenants making 100 percent or below the city’s area median income. The Honolulu City Council two weeks ago passed Bill 7, which creates a five-year pilot program to allow small apartment buildings to be built on lots of 20,000 square feet or less, with higher density and smaller setbacks…