Update .gitignore
Update .gitignore

leodemoura/lean,soonhokong/travis_test,avigad/lean,eigengrau/lean,Kha/lean,avigad/lean,fgdorais/lean,htzh/lean,codyroux/lean0.1,johoelzl/lean,javra/lean,fpvandoorn/lean,sp3ctum/lean,johoelzl/lean,fpvandoorn/lean2,dselsam/lean,leodemoura/lean,c-cube/lean,soonhokong/lean-osx,Kha/lean,fpvandoorn/lean,levnach/lean,rlewis1988/lean,levnach/lean,UlrikBuchholtz/lean,soonhokong/lean-windows,soonhokong/lean-osx,htzh/lean,digama0/lean,htzh/lean,soonhokong/lean,fpvandoorn/lean,soonhokong/lean-windows,leodemoura/lean,c-cube/lean,digama0/lean,soonhokong/lean,rlewis1988/lean,Kha/lean,digama0/lean,dselsam/lean,soonhokong/lean-osx,levnach/lean,fgdorais/lean,leanprover/lean,avigad/lean,soonhokong/lean-windows,soonhokong/travis_test,digama0/lean,javra/lean,dselsam/lean,leanprover/lean,johoelzl/lean,javra/lean,dselsam/lean,c-cube/lean,rlewis1988/lean,fpvandoorn/lean2,soonhokong/lean,avigad/lean,fgdorais/lean,Kha/lean,soonhokong/lean,johoelzl/lean,htzh/lean,avigad/lean,soonhokong/lean-osx,sp3ctum/lean,dselsam/lean,leanprover/lean,leodemoura/lean,fpvandoorn/lean,leanprover-community/lean,levnach/lean,digama0/lean,Kha/lean,javra/lean,rlewis1988/lean,leanprover-community/lean,sp3ctum/lean,sp3ctum/lean,htzh/lean,codyroux/lean0.1,javra/lean,leanprover-community/lean,soonhokong/lean-osx,UlrikBuchholtz/lean,UlrikBuchholtz/lean,leanprover/lean,leodemoura/lean,fpvandoorn/lean2,fpvandoorn/lean2,soonhokong/travis_test,leanprover-community/lean,leanprover/lean,johoelzl/lean,leanprover-community/lean,c-cube/lean,leanprover-community/lean,leodemoura/lean,digama0/lean,sp3ctum/lean,eigengrau/lean,soonhokong/lean-windows,fgdorais/lean,c-cube/lean,johoelzl/lean,avigad/lean,UlrikBuchholtz/lean,soonhokong/lean-windows,fpvandoorn/lean,Kha/lean,soonhokong/lean,eigengrau/lean,codyroux/lean0.1,fpvandoorn/lean,eigengrau/lean,eigengrau/lean,fgdorais/lean,soonhokong/travis_test,codyroux/lean0.1,rlewis1988/lean,rlewis1988/lean,fpvandoorn/lean2,UlrikBuchholtz/lean,leanprover/lean,levnach/lean,fgdorais/lean,dselsam/lean