Rename IQ.ELEMENT to IQ.IQ_ELEMENT

to avoid confusion between the IQ element 'iq' and the IQs child
element. ELEMENT defined in an IQ sublcass should contain the *child*
element.

Add element to StreamInitation and fix FileTransferManager which still
used a packet listener instead of an IQ request handler to handle
incoming stream initiation requests.

smack-bosh/src/main/java/org/jivesoftware/smack/bosh/XMPPBOSHConnection.java

@@ -543,7 +543,7 @@ public class XMPPBOSHConnection extends AbstractXMPPConnection {
                             String name = parser.getName();
                             switch (name) {
                             case Message.ELEMENT:
-                            case IQ.ELEMENT:
+                            case IQ.IQ_ELEMENT:
                             case Presence.ELEMENT:
                                 parseAndProcessStanza(parser);
                                 break;