v2.0.0

This was mostly an internal update to improve the development environment of
alchemist. This will hopefully make future feature development much easier for
both alchemist and it's plugins. There were however, enough changes to the
project in general that I felt it deserved a major version bump.

• moved entire codebase (as well as the plugins) to es6
• renamed alchemist.light to alchemist.lite for brevity
• stopped tacking on the version number to the end of builds
• dist/alchemist-node.js will now be the entry point for node developers (at
  least until node has es6 support)
• moved build system to the gulp 4 branch
• added a gulp-summary of all tasks
• improved build system all around
• All tests now runs all plugin's tests as well