This is the smallest possible thing that could work for both the local
development case and the case where we are targeting the Pulumi
Service.
Pulling down the pulumiframework and component packages here is a bit
of a feel bad, but we plan to rework the model soon enough to a
provider model which will remove the need for us to hold on to this
code (and will bring back the factoring where the CLI does not have
baked in knowledge of the Pulumi Cloud Framework).
Fixes#527
This change introduces an abstraction for a `backend` which manages
the implementation of some CLI commands. As part of defining the
interface, we introduce a new local backend implementation that just
uses data local to the machine.
This will let us share argument parsing and some display information
between the local case and the pulumi.com case in the CLI. We can
continue to refine this interface over time (e.g. today we have the
implementation of the Destroy/Update/Preview actually writing output
but instead they should be returning strongly typed data that the CLI
knows how to display and is unified across Pulumi.com deploys and
local deploys).
But this is a good first step.
