Remove background page dependency (stop the "running in background" message)

[capeterson]

Grey tab currently uses a background page to cache organization metadata and internal log messages. There's an alternative, event pages (and the alarms API to replace our use of setInterval()) which only live as long as they need to and don't trigger this warning.

It's a fair bit of code to update, and we'd have to cache in localStorage or the like, but it should lower memory use and fix the scary message about running when chrome is fixed that shows up on windows.