Compacting directory structure

Moving few files and directories around.

Grouping things for developing amber itself to `internals` directory (and exempting it from npm and bower), moving css & images for legacy IDE in `support/resources` etc.

The result is less scary because less directories and files are in root.

Also deprecating `amber_css` mapping that is there for one lone file.

The only 'drawback' is developers of Amber itself must run `http://localhost:4000/internal/` instead of plain `http://localhost:4000/`. Users of Amber are not touched.