Use Case: Using "Required Container Feature" to describe Node Impl. requirements (on host container)

How does Required Container Feature interact with node impls. so that a given implementation will be based on the container must be able to support executing them.

Example:
An app. requires specific (proprietary) APIs to deploy am image to a VM, this could be a public API for one impl. while another impl. could require an API of a vendor-specific virtual image library.

Notes:
Travis: Node Type Implementations include RequiredContainerFeatures, but this is not used in the examples. As it stands today, it seems to be implying one or all of the following assumptions:
1) You have to look at both the artifact types and the required container features to determine if a node type implementation is actually supported.
2) There isn't any normative set of required container features.
Matt: We left off a discussion of this suggesting that artifacts may export reqs/caps (as do node types).
Matt: 2 scenarios? one for artifact exec. support, one for container (environment) for APIs?

This JIRA issue is intended to develop the second scenario/use case focusing on specific APIs (provided by host environment or container) a certain node requires,

Reference:
https://www.oasis-open.org/apps/org/workgroup/tosca-interop/download.php/48640/ArtifactTypes_RequiredContainerFeatures%20-%20HP.pptx