messages now accessing their backend via the .backend property, rather than _backend attribute
messages now accessing their backend via the .backend property,
rather than _backend attribute

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