MDL-42666 repository_boxnet: Convert repository to APIv2
MDL-42666 repository_boxnet: Function to convert APIv1 references to true copies
MDL-42666 repository_boxnet: Tool to launch the migration
MDL-42666 repository_boxnet: Advise the user to run the migration tool
MDL-42666 repository_boxnet: Disabling file references
MDL-42666 repository_boxnet: Remove hardcoded date for APIv1 end of life
MDL-42666 oauthlib: Getter methods for accesstoken, client id and secret
MDL-42666 repository_boxnet: Revoke access token when logging out
MDL-42666 repository_boxnet: Alert the admins of the migration process
MDL-42666 repository_boxnet: Warn on HTTPS requirement when non HTTPS
MDL-42666 repository_boxnet: Minor tweaks of PHP Docs