Two ways to use the library: advanced compilation (prod) or raw/concatenated (dev)

This reduces the number of ways we support using the library.  While it is possible to build the library with a dizzying array of options, it is designed to be used with `ADVANCED_OPTIMIZATIONS` in production.  We also offer a way to debug the library during development.

These changes remove the following build targets:

 * `build/ol-whitespace.js` (replaced by `build/ol-debug.js`)
 * `build/ol-simple.js`
 * `build/ol-all.js`

The `build/ol-debug.js` target can be used as a single script for debugging (this was not the case with `build/ol-whitespace.js`).  The `build/ol-whitespace.js` target [generated `404s`](https://groups.google.com/forum/#!msg/ol3-dev/WrDx2zUaleU/Vl3gtybPHtIJ) while trying to fetch `deps.js`.  The `build/ol-simple.js` and `build/ol-all.js` targets were ways that we demonstrated we could exercise the Compiler, and provided no real value in my opinion.