clear input in demo projects

[pouya-abbassi]

I know it's not really huge bug and I know it's not a critical issue.
But it bothers me anyway.

In file demos/websocket/static/chat.js line 36 should be changed from:

form.find("input[type=text]").val("").select();

to:

$("#message").val("").select();

in order to really clear input and set focus on it.

[bdarnell]

Fixed in #2441