The `app/win/codesign` script should take a path to a file and a
description (`/d` parameter to `signtool.exe`) and sign the file using
whatever process the certificate authority requires.
* Remove gulp, replace with custom scripts
* Symlink entire dirs where possible (fixes#1232)
* Significantly speed up subsequent builds (fixes#1238)
* Watch process now observes new/removed files, not only changed
* Add ignoreMask, exclude all files with names starting with a #
* Better logging during builds
* Update travis.yml to use new, non-gulp-based build
* Add a multi-process, gulp-based build system to support es6 features,
async/await, jsx and scss
* Add a package.json to support dependency management and allow starting
the build process via npm
* Replace embedded Bluebird library with npm-installed one
* Add react, react-dom and web-library
* Introduce a custom require() loader in include.js as well as a minimal
local require() implementation in various other places
