Add note about origin handling in echo_wsh.py.
Add note about origin handling in echo_wsh.py.

BUG= http://code.google.com/p/pywebsocket/issues/detail?id=75
Review URL: http://codereview.appspot.com/5450120

git-svn-id: a751b5b3dcfba0ee4592a85c40d2fdd063ca0d53@605 4ff78f4a-9131-11de-b045-6380ec9940d4

XiaonuoGantan/pywebsocket,XiaonuoGantan/pywebsocket