Call a XenAPI plugin on this host

Return value
	type	description
	string	Result from the plugin
Parameters
name	type	description
session_id	session	valid session reference
host	host	The host
plugin	string	The name of the plugin
fn	string	The name of the function within the plugin
args	Map[string,string]	Arguments for the function
Errors
name	arguments	description

• Message has both a synchronous and asynchronous version
• This is a custom message