Remove old code from Proxy.

* this getinitargs was needed way back when there was old style classes. Not needed anymore.
Fix crash related to a missing __getnewargs__ method.

* Pyro (as most code) uses new style classes, Proxy inherits from DynamicProxy
  which is a new style class. As Proxies need to be serialized, pickle asks for
  this __getnewargs__. We could either raise AttributeError (pickle will assume
  empty tuple) or just return an empty tuple ourself, I am doing the latter.