John Langford <jl@hunch.net>
... and many others.  The git log includes at least:

 Alekh Agarwal
 Ales Tamchyna
 Alex Grubb
 Alexander K. Hudek
 Ariel Faigon
 Ben Gimpert
 Bharath Krishnan
 Brian Muller
 Chris Quirk
 Daniel Erenrich
 Daniel Hsu
 Eric Whyne
 Gabriel Synnaeve
 Gordon Rios
 Hal Daume III
 Harry Robertson
 HaveF
 Ivan Dyedov
 Jacob Hofman
 Jake Hofman
 Jan Szumiec
 Jarrod R Parker
 John Langford
 Lihong Li
 Luis Pedro Coelho
 Marcel Laverdet
 Martin Thomas
 Matthew Hoffman
 Nick Nussbaum
 Nikos Karampatziakis
 Nirupama Chandrasekaran
 Parag Agrawal
 Paul Mineiro
 Rob Zinkov
 Rukshan Batuwitage
 Sam Lendle
 Sergei Matusevich
 Shravan M Narayanamurthy
 Stephane Ross
 Stephen Merity
 Vaclav Petricek
 Yaroslav Halchenko
 Zhen Qin