Raise NotFound in software_config_get/software_deployment_get

This change results in the required behaviour of show_software_config
and show_software_deployment which will now also raising NotFound if
no entity with the ID was found.

partial blueprint hot-software-config-rest

Change-Id: I297a4a2a0592f1b60fe9bef0e097abe73cf57d75
RPC method to fetch deployments metadata

This method returns a list of software configs which are currently
deployed to a given server. Each config has the deployment input values
and current action inserted into it. This means that each config is
ephemeral and derived from the canonical config specified in the deployment
resource. The list of configs is sorted by config name. This allows the
template to control what order the configs are returned by setting the
'name' attribute of each deployment resource.

Having a separate RPC (and REST) method for deployment metadata also means
that servers will eventually be able to poll for deployment metadata directly,
avoiding the need to parse the stack for every poll.

partial blueprint hot-software-config-rest

Change-Id: I374f1e15d5255a3ad1264859fd845265cc60f218
Merge "Raise NotFound in software_config_get/software_deployment_get"
Merge "RPC method to fetch deployments metadata"