[Twisted-Python] Banana greeting and profiles

[Itamar Shtull-Trauring]

In the new banana, it starts out by sending a message with a list of 
profiles it supports:

    ["pb", "none"]

Now, the thing is, the "pb" profile doesn't imply you're running the PB 
protocol, it just means that you're defining some extra banana types that 
are used by the PB protocol, but for all you know this server may be running 
a different protocol. This is especially true when you get this list:

    ["none"]

So, you know it's using banana - but what protocol is running on *top* of 
banana?

As I'm seeing from HTTP, telling the client what protocol you run is rather 
important.

So, this implies that maybe the banana greeting should also include the 
protocol that it is running on top of Banana in it's greeting:

     ["Perspective Broker v6", ["pb", "none"]]