removed AJAX_PROXY_* settings.
removed AJAX_PROXY_* settings.

those don't really belong here, since they're contrib, and not core.
until very recently, though, there was no sane alternative.

caktus/rapidsms,ehealthafrica-ci/rapidsms,ken-muturi/rapidsms,ken-muturi/rapidsms,rapidsms/rapidsms-core-dev,eHealthAfrica/rapidsms,rapidsms/rapidsms-core-dev,lsgunth/rapidsms,dimagi/rapidsms,dimagi/rapidsms-core-dev,dimagi/rapidsms,catalpainternational/rapidsms,catalpainternational/rapidsms,lsgunth/rapidsms,unicefuganda/edtrac,unicefuganda/edtrac,dimagi/rapidsms-core-dev,caktus/rapidsms,caktus/rapidsms,peterayeni/rapidsms,lsgunth/rapidsms,eHealthAfrica/rapidsms,ken-muturi/rapidsms,ehealthafrica-ci/rapidsms,peterayeni/rapidsms,eHealthAfrica/rapidsms,ehealthafrica-ci/rapidsms,catalpainternational/rapidsms,unicefuganda/edtrac,lsgunth/rapidsms,peterayeni/rapidsms,catalpainternational/rapidsms,peterayeni/rapidsms