Accept 202 as valid code for /system/scale-function/<function>
Accept 202 as valid code for /system/scale-function/<function>

Updated gateway to accept 202 as valid response code for
/system/scale-function/<function> along with 200.

Fixes: #faas-netes/245

Signed-off-by: Vivek Singh <0309897457bdbaf8410ee5929728bb5df02fed57@yahoo.in>

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