Libxmljs Versions Save

• Fixes AppVeyor HTTPS issue caused by NPM config

• Fix #449 (Isolate::IsDead, Nan::NewInstance)
• Fix #451 (_snprintf macro)
• Fix AppVeyor builds for Node v4 on win32
• Latest node-gyp for builds/tests
• Latest node-pre-gyp

• Additional precompiled binary architectures for Windows
• Added AppVeyor test to verify working binaries
• Upload binaries as .tar.gz
• Simplified appveyor.yml

Added support for precompiled Windows binaries.

Changes since 0.15.0:

Document#type(), Document.fromHtml() Node#namespace(ns) returns node Node#namespaces(true) returns only locally-defined namespaces Comment nodes no longer escape content as XML Exposed xmlMemUsed as .memoryUsage() Fixed various memory issues