Provide and add "commercial" images per Essentials Plugin

To promote Essentials plugins (features and tools) in Essentials' Library, we want to display some images per plugin. mpeerdeman] Please provide these images, then reassign to Marijan or Tobi to include them in Essentials.

Discussed was that as long as the plugins are actually part of the Essentials web app, the images should be there too. When plugins move to the forge, the images could be served through the plugin's site on the forge.