mingw-w64 support (uNetworking#510)

* mingw32 support

* refactored to use __builtin_bswap64(x) on mingw, thread-specifier moved to MSVC block

Node.js: add getResponsePrototype, getRequestPrototype again

Fix addWebSocket / addHttpSocket interference

Make HttpSocket::upgrade, Hub::upgrade always succeed

Add timeOut, isTimingOut, basic documentation to HttpSocket.h

Using Hub::onHttpUpgrade

Restructure http flow, fix some buffering bugs

Update Node.js addon

Bump to v0.12.0

Bump to v0.11.2