It’s been more than a year since the owners of Westfield Montgomery mall revealed plans for a massive redevelopment project. The work was supposed to begin last spring, but so far nothing has happened. Why not? Because the county recently banned the construction of new housing in neighborhoods where the schools are already overcrowded — and that includes the Walter Johnson High School cluster near the mall. The year-long residential building moratorium, which began July 1, is intended to slow down the flow of new students while MCPS figures out how to manage them. The mall’s redevelopment plan calls for more than 700 new apartments and condos along with office space, a hotel, a huge new gym and an outdoor shopping and dining area. But none of it is going to happen, we’re told, until the housing component can move forward.