[BROKEN] Implement basics of chrome.usb
It works! Kinda...
Make the USB stuff functional.

It's currently mostly un-tested though...
oopsie, included a thingy that doesn't work.
Remove the compiled stuff.
Merge branch 'implement-usb' of github.com:AmandaCameron/chrome.dart into implement-usb
adding the chrome.pushMessaging API + tests
minor tweaks
Merge pull request #26 from dart-gde/pushMessaging

adding chrome.pushMessaging
Merge pull request #25 from AmandaCameron/implement-usb

Implements USB, I think
Merge branch 'master' of github.com:dart-gde/chrome.dart