Support Docker Trust or equivalent workflow

[dtzar]

docker trust currently works utilizing notary v1. We should have an equivalent workflow or support utilizing native docker integration with the notary v2 bits.

I realize this crosses a number of specification areas (i.e. trust store, etc). Would be good flush out the sub-requirements on this issue.

[andyfeller]

@dtzar : have you had a chance to catch up on @SteveLasker and @justincormack presentation from recent Kubecon and notary v2?

what from this presentation makes sense to capture in this repository versus living elsewhere?

[dtzar]

Docker extension for notary is an option. There was a POC here, but wanted to remove it since it wasn't currently under active development.