* Specify MinCount/MaxCount when creating an EC2 instance. These
are required properties on the RunInstances API.
* Only attempt to unmarshal egressArray/ingressArray when non-nil.
* Remember the context object on the instanceProvider.
* Move the moniker and object maps into the shared context object.
* Marshal object monikers as the resource IDs to which they refer,
since monikers are useless on "the other side" of the RPC boundary.
This ensures that, for example, the AWS provider gets IDs it can use.
* Add some paranoia assertions.