There is a race where the registerEventHandler() server call may happen in
a different thread to the main UI, causing the main UI to see
httplib.CannotSendRequest exceptions.
This moves the call into the main thread, removing the init race and fixing
errors I was seeing with the xmlrpc backend.
(Bitbake rev: 14cdd3b351d1ab23cb3ea5f853e403a53e67ac1c)
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>