Added os.TempDir() to replace using '/tmp/' to make the tempdir cross platform
Added os.TempDir() to replace using '/tmp/' to make the tempdir cross platform

Signed-off-by: Franklin Harding <2ffecade5c776fcb1c419d0232824cfd13db4423@gmail.com>

rgee0/faas,haru01/faas,haru01/faas,openfaas/faas,rgee0/faas,rgee0/faas,haru01/faas,rgee0/faas,rgee0/faas,haru01/faas,haru01/faas,alexellis/faas,alexellis/faas,rgee0/faas,alexellis/faas,haru01/faas,openfaas/faas,rgee0/faas,alexellis/faas,rgee0/faas,alexellis/faas,alexellis/faas,rgee0/faas,alexellis/faas,haru01/faas,alexellis/faas,rgee0/faas,openfaas/faas,haru01/faas,alexellis/faas,haru01/faas