add rake task: update_contributors
add rake task: update_contributors

onehub/fakefs,lgierth/fakefs,anthonyryan1/fakefs,vhl/fakefs,bquorning/fakefs,eventualbuddha/fakefs,deployable/fakefs,marxarelli/fakefs,fakefs/fakefs,zimbatm/fakefs,bf4/fakefs,moretea/fakefs,pivotal-cf-experimental/fakefs,openSUSE/fakefs,1234-/fakefs,dekz/fakefs,defunkt/fakefs