Add a constructor method for Backend
Add a constructor method for Backend

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