[WIP]collect aws cloudformation templates and stacks at Amazon refreshing

We shouldn't be creating any DB records during the parsing phase of the refresh.  The point of the 2-phase approach to refreshing is to separate out the parsing logic from the DB storage logic.

If we create objects here, we lose the ability to batch the DB inserts later.  In other words, we will have a number of inserts happening outside of the batching logic in `save_inventory.rb`, which will slow down the parsing process.