rewrite in co generators

rewritten with the following changes:

- use [cogent](https://github.com/cojs/cogent) instead of super agent. we can switch back to super agent if it gets fixed.
  - handles gzip
  - handles redirects
- use graceful-fs over fs
- remove auth stuff (re-add after everything else works)
- remove proxy stuff (re-add after everything else works)

to do:

- [ ] readd auth stuff - i need tests
- [ ] readd proxy stuff - i need tests
- [ ] reimplement old api - changed it a little, but there's no need for that. we can change it later.

right now it works, but there are a lot of tests to be had. it's already much cleaner.