Escape % in eventsource to prevent decoding problems

Since `decodeUri` is used on client side, we should escape % to prevent problems.

See sockjs/sockjs-client#490 for a reported issue.

Author: brycekahle

src/trans-eventsource.coffee

@@ -14,7 +14,7 @@ class EventSourceReceiver extends transport.ResponseReceiver
     doSendFrame: (payload) ->
         # Beware of leading whitespace
         data = ['data: ',
-                utils.escape_selected(payload, '\r\n\x00'),
+                utils.escape_selected(payload, '%\r\n\x00'),
                 '\r\n\r\n']
         super(data.join(''))