Merge pull request #270 from jitsi/fix-sip-call

Fixes sip calling.

modules/xmpp/strophe.rayo.js

                 value: roomName
             }).up();
 
-            if (roomPass !== null && roomPass.length) {
+            if (roomPass && roomPass.length) {
                 req.c('header', {
                     name: 'JvbRoomPassword',
                     value: roomPass