Boys play football in a shantytown of Olinda, about 18 km from Recife in northeastern Brazil, on June 18, 2013 as the FIFA Confederations Cup Brazil 2013 football tournament is being held in the country. The historic centre of Olinda is listed as an UNESCO World Heritage Site. (Photo by Yasuyoshi Chiba/AFP Photo)

A woman looks out of a dusty window after boarding a bus to be transported to see the casket of Nelson Mandela at the Union Buildings in Pretoria, South Africa, Wednesday December 11, 2013. On Thursday, December 5, 2013, Mandela died at the age of 95. (Photo by Markus Schreiber/AP Photo)

A boy poses with a butterfly on his face during a photocall to promote the “Sensational Butterflies” exhibition at the Natural History Museum in central London, on March 25, 2013. With around 400 live tropical butterflies and moths living in the temporary facility, visitors will get the chance to see them flying freely as well as looking for emerging butterflies at the hatchery window. Running from March 29 to September 15, 2013, the exhibition is housed in a structure in the museum grounds. (Photo by Leon Neal/AFP Photo)

A man jokingly poses with a new installation of British graffiti artist Banksy's art in New York, October 20, 2013. (Photo by Carlo Allegri/Reuters)

A female member of the Ahbab Al-Mustafa Battalion holds a gun as she undergoes military training in Aleppo's Salaheddine district, June 24, 2013. (Photo by Muzaffar Salman/Reuters)

Musher Michael Ruopp of Germany starts with his sled dogs at the 23rd International Sled Dog Race in Oberhof, central Germany, Sunday, February 24, 2013. (Photo by Jens Meyer/AP Photo)

Edward Nunn of the USA, Toney Freeman of the USA and Dexter Jackson of the USA pose during the IFBB Australia Pro Grand Prix XII at The Plenary on March 9, 2013 in Melbourne, Australia. (Photo by Robert Cianflone)

Dustin Murley (L) and Jessey Sisson race on their ostriches during the annual Ostrich Festival in Chandler, Arizona March 10, 2013. (Photo by Joshua Lott/Reuters)