Remote.update() didn't pass kwargs along to git command.
Remote.update() didn't pass kwargs along to git command.

Fixes #250

beni55/GitPython,manasdk/GitPython,manasdk/GitPython,breavo/GitPython,h4ck3rm1k3/GitPython,zsjohny/GitPython,cdht/GitPython,zsjohny/GitPython,roidelapluie/GitPython,expobrain/GitPython,bwrsandman/GitPython,zsjohny/GitPython,bwrsandman/GitPython,gitpython-developers/gitpython,nvie/GitPython,pengshp/GitPython,pengshp/GitPython,StyXman/GitPython,gitpython-developers/GitPython,pengshp/GitPython,StyXman/GitPython,h4ck3rm1k3/GitPython,expobrain/GitPython,avinassh/GitPython,jeblair/GitPython,beni55/GitPython,dpursehouse/GitPython,StyXman/GitPython,cdht/GitPython,ghtdak/GitPython,dpursehouse/GitPython,cdht/GitPython,jeblair/GitPython,avinassh/GitPython,roidelapluie/GitPython,gitpython-developers/gitpython,bwrsandman/GitPython,ghtdak/GitPython,nvie/GitPython,gitpython-developers/GitPython,breavo/GitPython,avinassh/GitPython