The `node.getLevelNamingScheme` and the `node.setLevelNamingScheme`
methods will be removed in `enb@2.0.0`.

Got rid of scheme builders

Redundant code of deps

Remove deprecated techs

Remove deprecated options

The `mock-fs` does not support `require` for Node.js 4.

Because of this test failed with error:

```
Cannot find module 'path/to/file.js
```

Support Node.js 4

**Example of new format:**

```
{
    button__text: [
        {
            entity: { block: ‘button’, elem: ‘text’ },
            tech: ‘css’,
            path: ‘path/to/file.ext’,
            level: ‘path/to/level’
        },
        /* ... */
    ],
    /* ... */
}
```

With this introspection format to easily get a list of files named
entity.

**What has been done?**

* Use `bem-walk` to scan levels.
* Use `bem-naming` to get id of BEM entity.
* Add `BundleIntrospection` class to work with introspection of levels
for one bundle.
* Rewrite `levels` tech with `build-flow`.
* Use promises with `node.buildState` to avoid scanning the same levels
multiple times.
* Don't read files for directories (example i18n), it should do `files` tech.

Now the `bem-walk` is used to scan.

Exactly the same benchmarks in `bem-walk` repository

Introspection Format

API moved to bottom of list

Remove 'docs/bem-project.md' file

Used the `files` field in `package.json`

Replaced *.bemhtml with *.bemhtml.js [issue 404]

…rsect