Add Web fun so admin can see the list of all GraveChest that are unclaimed

At some point need to add web interactions so that admins can control the plugin.

Needs to have following stuff:
1. List of all GraveChests with owner, world, location.
2. Some type of removal process with single and mass chest selections.
3. Some type of other fun that would be easier to handle from the web than console/in game commands.
