mod_carbons_copies: Initial commit; allow the user to enable v0 style carbons for clients which are not carbons-capable yet. This will not interfere with clients which have support for regular Message Carbons (XEP-0280). This module takes two optional parameters: carbons_copies_default - if set to true, copies will be enabled by default carbons_copies_adhoc - Enable Adhoc-commands to allow the user to enable/disable copies