Add webpack config for bempack

[Yeti-or]

TODO:

• [ ] add webpack build process to README.md
• [ ] move bh-render-plugin to separate package
• [ ] add support for bem-xjst
• [ ] depsByTech
• [x] webpack 2
• [ ] webpack 3

good to have:

• custom bem-naming
• custom bem-fs-scheme
• support bem-config

[tadatuta]

Looks fine for WIP but I don't want to merge it in current state. Let's keep it in brunch for some time?

[Yeti-or]

webpack:

du -h desktop.bundles/index/index.min.js
396K    desktop.bundles/index/index.min.js

enb:

du -h desktop.bundles/index/index.min.js
248K    desktop.bundles/index/index.min.js

but we could do it: 💪