Make the port optional in <streamhost/>

XEP-0065 section 9.2 says “The "port" attribute specifies the port to
connect to.  This attribute MAY be present.  The value MUST be a valid
port number in decimal form.  If not specified, the port value is
"1080" (in accordance with RFC 1928).”

This fixes a traceback when a streamhost is advertised with the default
port.

src/common/proxy65_manager.py

@@ -84,9 +84,13 @@ class Proxy65Manager:
         for item in query.getChildren():
             if item.getName() == 'streamhost':
                 host = item.getAttr('host')
-                port = item.getAttr('port')
                 jid = item.getAttr('jid')
-                if not host or not port or not jid:
+                port = item.getAttr('port')
+                try:
+                    port = int(port)
+                except ValueError, TypeError:
+                    port = 1080
+                if not host or not jid:
                     self.proxies[proxy]._on_connect_failure()
                 self.proxies[proxy].resolve_result(host, port, jid)
                 # we can have only one streamhost