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
Ok, but can yu still explain me why not just do
```struct Factory<v8::FunctionTemplate> : FactoryBase<v8::FunctionTemplate> {```
instead of 
```struct Factory<v8::FunctionTemplate> : public FactoryBase<v8::FunctionTemplate> {```
Is the explicitness a style thing?