Tigase stanza error

It quick and a bit dirty fix, but hope this will help fix the problem.
Tigase is really wide used XMPP server and I think you should not miss opportunity to support it also.
The problem was here with priority of child nodes in `<stream:features stanza>`
It was looking like this:

```xml
<features>
    <ver xmlns="urn:xmpp:features:rosterver"/>
    <session xmlns="urn:ietf:params:xml:ns:xmpp-session"/>
    <bind xmlns="urn:ietf:params:xml:ns:xmpp-bind"/>
 </features>
```

Tigase can't create session before binding.
I solve this problem by sorting child nodes to move `<bind/>` before `<session/>` request.
Maybe this is not the best way, but we found a root of the problem.