Miles Hamby of Alexandria took last place in the annual Bastille Day Races Monday at the 34th Annual Waiters Race at Brasserie Les Halles downtown. Hamby, though not a waiter, crashed the race dressed as one all for a good cause.  The year’s race down Pennsylvannia Avenue benefited Best Buddies, an organization founded by Anthony Shriver and dedicated to enhancing  the lives of  people with intellectual disabilities. Runners carried bottles of  Volvic Mineral Water, the race sponsor, instead of the traditional bottles of champagne.   A Les Halles server, Macs Smith, 19, and a student at William & Mary won the coveted honor. Smith, left, is from Annandale, and plans to study at the Sorbonne.