When generating SQL for new models, EvolveAppTask was lumping together

the SQL for the model creation and for any constraints/indexes. This

could be fine a lot of the time, but depending on the complexity of the

upgrade, that deferred SQL could fail.
A sample scenario would be an app creating a model that has a reference

to an existing model, but to a newer Primary Key type that would be (but

hasn't yet been) evolved on the target model.
We now separately track the model creation SQL and the deferred SQL. All

deferred SQL is executed once all evolutions and migrations have

concluded.

All unit tests pass for all databases.
Verified this fixed a messy upgrade issue with Review Board 4 -> 5.