move package build system to gulp (bug 1077585)

**Practical benefits over the Makefile**

- Centralized configuration of different packages for different servers
- Whitelist is now a list of globs rather than every file listed individually
- Less hacks (sed, TMP folder)
- Use of a settings template rather than having a separate settings file for each server in our ```src```
- Use of a manifest template rather than ```sed```ing URLs over URLs
- Theoretically faster as it has some concurrency and involves less I/O
- Paves the way for Yulelog Gulp builds (currently hacky, involves ```sed```ing URLs over URLs)
- Dynamic checks on what languages are supported to only load needed locales
- Easier to maintain and more flexible than a Makefile
- Cleaner package/version names (e.g., ```prod_20141031.123015``` vs ```Marketplace_prod_20141031123015```)

**Tasks**

- [x] pipe manifest and settings straight to package destination instead of using merge-stream
- [x] find out why JS isn't piping through
- [x] configure payments packages in config.js
- [x] run commonplace langpacks beforehand
- [x] only include needed languages
- [x] build settings_local_package into the JS bundle

**In a separate commit**

- yulelog
- remove unused images from the repo to decrease package size from 368KB (i glob them all)
damper had some similar path issues (a bunch of the contributors from the FB Open Academy were using Windows; that was difficult). but beyond that, everything worked fine with Windows. I'd imagine same here.