Add hook for dynamic endpoints on conversation definition.
Hook up dynamic conversation endpoints in view definitions.
Remove obsolete TODO.
Add start of hook for extra jsbox endpoints.
Fix reference to extra_static_endpoints in conversation view definition.
Implement extra endpoints for Javascript apps.
Put conversation extra_endpoints setting in the right place.
Add test for sms_tag checking and fix lookup of sms_tag value.
Use endpoints to determine whether sending is allowed.
Remove unnecessary temporary variable.
Merge branch 'feature/issue-607-dynamic-conversation-endpoints' into develop