If `global` is used and handlebars is compiled for browser
usage without a Node.js `global` polyfill, handlebars
fails with a `global is undefined` error.
Fixes#1593
Converts the tool chain to use babel, eslint, and webpack vs. the previous proprietary solutions.
Additionally begins enforcing additional linting concerns as well as updates the code to reflect these rules.
Fixes#855Fixes#993