add test plugin

Signed-off-by: John Else <john.else@citrix.com>
Add generic plugin cleanup function

Signed-off-by: John Else <john.else@citrix.com>
Remove redundant handling of Sys.Break

It's already handled by the main loop.

Signed-off-by: John Else <john.else@citrix.com>
Add interdomain version of the main loop

Signed-off-by: John Else <john.else@citrix.com>
Add runtime mode switch to dummy plugin

Signed-off-by: John Else <john.else@citrix.com>
use xenbus client

Signed-off-by: John Else <john.else@citrix.com>
undo xenbus

Signed-off-by: John Else <john.else@citrix.com>