Static assets support

[cliffano]

Dispatcher deployments often involve deploying static assets (images, etc) directly to docroot.
Sample static assets need to be included in aem-helloworld-publish-dispatcher and aem-helloworld-author-dispatcher. The deployer in aem-tools need to support copying static assets to docroot.

[cliffano]

Sample asset image earth.jpg is sourced from Nasa Image Galleries https://www.nasa.gov/image-feature/rocky-mountains-from-orbit , adhering to their Media Usage Guidelines https://www.nasa.gov/multimedia/guidelines/index.html .