Use uuid instead of tempfile.mkdtmp, which created an actual directory.
Use uuid instead of tempfile.mkdtmp, which created an actual directory.

That, over time, could have caused slow downs due to file-system hassle.

Fixes #258

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