fixing send_message calls + tests
Fix send_message command for surveys.
more explicit send_message function signature for http_api
more explicit send_message function signature for subscription app
Merge branch 'feature/issue-288-fix-send-message-command' of github.com:praekelt/vumi-go into feature/issue-288-fix-send-message-command
make sure we add the conv to the msg_options
fixing http_api tests
removing stray print
remove extra conversation_key
Merge branch 'feature/issue-288-fix-send-message-command' into develop