This change modifies the existing resource provider RPC interface slightly.
Instead of the Create API returning the bag of output properties, we will
rely on the Get API to do so. As a result, this change takes an initial
whack at implementing Get on all existing AWS resources. The Get API needs
to return a fully populated structure containing all inputs and outputs.
Believe it or not, this is actually part of pulumi/lumi#90.
This was done because just returning output properties is insufficient.
Any input properties that weren't supplied may have default values, for
example, and it is wholly reasonable to expect Lumi scripts to depend on
those values in addition to output values.
This isn't fully functional in its current form, because doing this
change turned up many other related changes required to enable output
properties. For instance, at the moment resource properties are defined
in terms of `resource.URN`s, and yet unfortunately the provider side
knows nothing of URNs (instead preferring to deal in `resource.ID`s).
I am going to handle that in a subsequent isolated change, since it will
have far-reaching implications beyond just modifying create and get.
