Rewrite make_global_whitelist to use the datatracker api

[rjsparks]

trafficstars

Right now, /a/postconfirm/make_global_whitelist invokes django code from the deployed datatracker directly, but it is not part of the datatracker source tree.

It should be rewritten to query the API instead and remove its dependency on django.

[larseggert]

And s/white/allow/g