Add delivery class inference and injection into inbound messages for JsBoxApplication
Change the dialogue app's vumi_app.js to store a user's answer to choice and freetext states
Pass store_as directly to store_answer() instead of passing in state_description, wait for a user's answer to be stored before getting the next state
Fix delivery_class inference for smpp transport_type (it should map to sms, not ussd)
Return p.then() for store_answer instead of using then(), then returning p
Merge branch 'develop-frontend' into feature/issue-589-implement-display-this-question-in-search-results-in-dialogue-vumi-app-js