Facebook has leased 730,000 square feet at the Farley Building, grabbing up all of the West Side property's office space. Facebook (NASDAQ: FB) and the building's owner, Vornado Realty Trust, announced the deal Monday. The Farley Building is the cornerstone of what Vornado is calling the Penn District. Vornado is in the middle of a $2 billion-plus project to redevelop more than 5 million square feet in the neighborhood around Penn Station and Madison Square Garden. "Facebook’s commitment to…