Add methods for retrieving conversation definitions.
Add hooks for generic conversation and router actions to the Go API.
Merge branch 'develop-frontend' into feature/issue-335-add-poll-support-to-go-api
Add default API action dispatchers to conversation and router definitions.
Actually commit the action dispatcher module.
Fix up action error handling and improve tests.
Start action_dispatcher tests.
Add tests for unknown_action and dispatching to action handlers that generate exceptions.
Properly handle actions that return deferreds and add test for successful action dispatching.
Start of dialogue API actions.
Implement poll saving and getting.
Add tests for get_poll and save_poll.
Hook up loading of model_data for dialogues.
Hook up diagram saving (possibly incorrectly).
Test the dispatcher_type_name is used in error messages and remove quotes from around type name in error messages (for readability).
Add conversation_key to model_data for dialogue.
Epic refactor to make conversation and router APIs look nicer.
Tests and bugfixes for the new action handler classes.
Protect get_conversation_definition against multi_surveys which is undefinable.
Put back base classes and skip conversation types that don't have a conversation definition (i.e. multi_surveys).