Callback on offline Plugin Changelog
1.2 -- December 15, 2017
    - Sending POST request instead of GET
 
    - Parameters are send as JSON body instead of query params.
 
    - Added "plugin.callback_on_offline.send_body" to enable/disable sending message body. True by default.
 
    - Slightly improved logging.
 
1.1 -- December 14, 2017
    - Added message body to the request. 
 
1.0 -- August 16, 2015