Adds the common/shared code to support notes in Shipyard such that this
component can be reused between the Shipyard API and the workflows.
Includes a single example of creating and retreiving notes as part of
action creation, that will likely be changed in a future change.
Note that this change doesn't include changes to the CLI to represent
notes outwardly, but the first example can be seen using the
--output-format=format option (shipyard get actions)
Change-Id: I2f87713eb74dae312912ff4c36e6ae30a569ea38
35d6089d32