Allow UUID definitions in the mappings JSON

Allow UUID definitions in the mappings JSON

Add support for reading the Widget invariant and version UUIDs from the
TOSCA mappings JSON. In this commit the artifact-generator.properties is
also read and used to provide default values. This step prevents any
existing deployments (e.g. automated test integration) from failing.
The redundant properties file will be deprecated in a future commit,
only when the JSON configuration has been updated.

Also remove two unused Java files to help with coverage stats.

Change-Id: Idc82e28092a2b028214225c7974db411c9f8a173
Issue-ID: AAI-2284
Signed-off-by: mark.j.leonard <mark.j.leonard@gmail.com>