Clean up gulp build files

[JFusco]

• Remove stage-2 from babelrc and add stage-0 so we can take advantage of function binding.
• Add global object in eslint and add __DEV__ and module
• Add gulp load plugins to the build to allow auto loading of plguins
• Separate out tasks in a gulp/tasks folder for separation of concerns and scalability.
• Add bridge.js file to load all plugins and pass appropriate settings to each task.
• Add gulp util for coloration and beepbeep for notification once the build is done.
• Add webpack progress bar plugin so we can see the status of a distribution build when webpack is running.
• Refactor gulpfile.babel.js to use gulp load plugins and update the tasks to use utils
• Add __DEV__ to webpack so we can easliy decide which code gets ripped out when doing prod builds
• Add example of using __DEV__ in Github.js class
• Add version and postversion tasks in package.json file so we can handle semver