A protester sprays paint on the window of a bank during a rally against Expo 2015 in Milan, Italy, April 30, 2015. The Milan Expo will open in the city on May 1. Officials are counting on some 20 million visitors to the six month-long exhibition of products and technologies from around the world. (Photo by Stefano Rellandini/Reuters)

Figurines representing French Brigade of Lancers are seen on a 40-square-metre miniature model of the June 18, 1815 Waterloo battlefield, in Diest, Belgium, in this picture taken on April 29, 2015. Waterloo enthusiast Willy Smout said he spent 40,000 hours and around 150,000 euros over the past 40 years, to recreate the battlefield as closely as possible in a purpose-built room in his house. (Photo by Francois Lenoir/Reuters)

A Buddhist monk catches an aerial view of Kathmandu from the damaged Swayambhunath Stupa premises in Kathmandu, Nepal, Wednesday, May 6, 2015. The April 25 earthquake killed thousands and injured many more as it flattened mountain villages and destroyed buildings and archaeological sites in Kathmandu. (Photo by Niranjan Shrestha/AP Photo)

The New World porcupine, family Erethizontidae, 1280 Gram born at 11 April 2015 Inventory in Zoo. Counting trade Fairs Weighing the Zoo is at 7 May 2015 too the 108 Birthday Zoo Hagenbeck Hamburg, Germany. (Photo by Imago/ZUMA Wire)

This Thursday, April 30, 2015 photo shows Lebanese citizens walking on the Corniche, or waterfront promenade in Beirut, Lebanon. This photo was shot through the lowered veil of a niqab, which is worn by some conservative Muslim women. The cloth allows women to follow a strict interpretation of their religious beliefs by preventing others from seeing their faces. (Photo by Hassan Ammar/AP Photo)

Alex Plunkett, left, and Sean Hart, both of Arlington, Va., join hundreds participating in the annual International Pillow Fight Day on April 5. Massive pillow fights broke out on the Mall in Washington and in cities around the world. (Photo by Marvin Joseph/The Washington Post)

New York City policemen tangled with demonstrators at a subway station on the opening day of the New York World's Fair, April 22, 1964. Youths attempted to stall the train, which was headed from the city to the fairgrounds, as a form of protest on behalf of civil rights for blacks. (Photo by Charles Gorry/AP Photo)

Two fourteen-week old lion cubs, a male named Ramzes and a female named Zara, are seen during a Christening ceremony at the Bojnice Zoo April 4, 2015. The two cubs are Barbary lions (Panthera leo leo), local media reported. (Photo by Radovan Stoklasa/Reuters)