Apply latest nuxeocli Nuxeo Packaging standards to nuxeo-sample-project

The latest nuxeocli Nuxeo Packaging standards are described here: https://doc.nuxeo.com/nxdoc/creating-nuxeo-packages. Sample project nuxeo-sample-project should be updated to conform to these standards. Specifically, the existing https://github.com/nuxeo/nuxeo-marketplace-sample project/git repo should be consolidated/refactored into being a package module within the https://github.com/nuxeo/nuxeo-sample-project project/git repo.

This change simplifies build version management and packaging for the Nuxeo Sample Project. It will also simplify efforts to develop a Nuxeo OpenShift S2I capability that are in progress in git repo https://github.com/nuxeo-sandbox/nuxeo-s2i.