NAN 1.5 WIP

This branch will become NAN 1.5.
Added Asyncworker #207 and new NanNew #210. Needs more testing with actual addons.
Now split into many files. Seems to work so far. Good news for nauv.h
Since we are in an internal namespace I'd go with something like:

````
typedef v8::FunctionTemplate FunctionTemplate;
template <>
struct Factory<FunctionTemplate> : public FactoryBase<FunctionTemplate> {
}
````