Ensure entities specified by user during trigger creation exist

[lilyjma]

Applies to Event Hub, Service Bus queue, Service Bus topic, and Cosmos triggers:

Users are prompted for info about the entity (event hub name, service bus queue name, topic/subscription name, Cosmos database and collection name), but these entities are not created for the user in the background, except strangely for the Cosmos database. If these specified entities don't exist, the follow exceptions are thrown during debugging (blocks of text that are hard to read - I took out the relevant sections):

Request:

1. Auto create entity in background if not already exist. OR
2. Leave comment in template telling users to ensure their referred entities exist before running code.

[ejizba]

This one is not specific to Node v4. It repros in the old model and other languages as well