added Http backend
added Http backend

Signed-off-by: unicefinnovation <0650239e34aa7009ad6f563abe6dad0ce88c321c@unicef.org>

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