adding support to build from `.js` files in a form of yui modules

## Goal

Often, yui apps contain a mash up of modules, some of them from core, some of them from gallery, some others from people who are not using shifter/yogi, from people who just write the modules using `YUI.add()` because that's easier, and in general, we usually end up with a very different structure.

The main goal is to be able to build any YUI module, even when the module does not have all the fancy configuration for builder. This is useful for apps and custom yui modules that were created outside of the yui modules workflow, and reduces the overhead of consolidating all modules for and application.

## Usage

```
shifter --build-dir path/to/build --config path/to/module-foo.js
```

This example will analyze `module-foo` to see if it is a YUI module (if it has the `YUI.add` statement) and collects all the info from that registration to build the sanitized versions, just like a regular build using `build.json`.

## Integration

This is going to be used extensively by `yogi-app` package in order to walk and build modules within an app.

## TODO

- Tests
- Docs