UPDATE: provider, addon.xml, CHANGELOG.txt, and README.txt updates

* Changed provider-name to RIVY
* Improved summary information, license information, and credits
* Removed redundant COPYING.txt file
UPDATE: improved icon; improved licensing disclosure language and add Moka attribution
UPDATE: self auto-updating support information added

* Added repository information to addon.xml
* Self auto-updating information is present, but is DISABLED (via comment in addon.xml)
* A repository addon is preferred, adding less confusion and clutter to the addon installation menus
UPDATE: version update, v2.3.1