Simplify boilerplate

[jhen0409]

• [x] Just use npm scripts instead of gulp
  • [x] webpack, webpack-dev-server, eslint, mocha, crx use CLI tool instead.
  • Move replace-webpack-code to webapck config, it's sync code of purely.
  • Don't use jade, just use chrome/*.html, dist/*.html.
  • No manifest.{env}.json, just use chrome/manifest.json, dist/manifest.json
• [x] Remove redux-devtools monitor dependencies, and recommend use redux-devtools-extension.
• [x] Implement all #8 tasks.

[oswaldoacauan]

any news on this?