Use v8::ArrayBuffer instead of node::Buffer

[kenny-y]

Suggest the substitution based on the following facts:

• v8::ArrayBuffer can own a buffer (delete the underlying raw buffer in dtor), or borrow a buffer with creation flag ArrayBufferCreationMode::kExternalized) (does not delete), so it's possible to reduce buffer deep copying when using v8::ArrayBuffer in user program
• It's easy to allocate views for v8::ArrayBuffer in C++ code, ref issue Typed array support #89

Ref:

1. https://github.com/nodejs/node/blob/master/src/node_buffer.h
2. https://v8docs.nodesource.com/node-6.9/d5/d6e/classv8_1_1_array_buffer.html

[kenny-y]

@halton @DonnaWuDongxia @tingshao @lisa0314 What do you think of the above issue?

[halton]

I do not have knowledge to discuss. :) you guys can decide.

[tingshao]

Nan:NewBuffer will take the owner ship of the input buffer. I have met with crashes due to double freed memory when ignored that behavior after adding destructor code for some classes. If the ownership can be configured in a explicit way, I think that may be better than the error-prune NewBuffer.