PoC: Split treemap UI from webpack analyzer code

[valscion]

This is a proof of concepts showcasing one approach of splitting the UI code from webpack code in a pluggable way as described in webpack-contrib#32 (comment)

This is how the directory tree would look like with this approach:

webpack-bundle-analyzer
├── reporter-treemap
│   ├── client
│   │   ├── components
│   │   └── vendor
│   ├── public
│   ├── views
│   └── webpack.config.js
├── src
│   ├── bin
│   └── chartData
└── test
    ├── bundles
    ├── src
    └── stats

[valscion]

This approach currently is breaking on Node 4 because the reporter-treemap directory is not being transpiled.

Please ignore this for now, as this is just a proof of concept. This approach works on Node 6 and up.