Rename author 'Y. Kushnir' to 'Yochanan Kushnir'

This author was "a contributing author to the
Intergovernmental Panel on Climate Change (IPCC) 2001
Third Assessment Report":
http://blogs.ei.columbia.edu/2012/04/03/faculty-profile-yochanan-kushnir/
http://www.ldeo.columbia.edu/~kushnir/

This name appears in AR5.