Fixed for V8 API change on `Set` & avoid VS build error LNK2005

Latest V8 API change removed the 3rd parameter of `Object::Set`. This fix renames `Set` with 3rd parameter to `ForceSet` for this change (See discussion rvagg/nan#221).

Also fixed for VS build error LNK2005 that some V8 functions are redefined. The fix is simply putting <node.h> before any other inlcude.