service worker needs to precache files

[davidmaxwaterman]

1. build app and run server
2. load app in chrome
3. turn off network
4. reload app - works fine since all resources on the main view are cached by the service worker
5. click on the memory hamburger button

expect:
it should display as if online

actual:
various resources are missing, and weren't access when online and so weren't cached. all resources need to be listed in the platinum-sw-cache precache attribute....perhaps they need to be bound as per the example :
https://github.com/PolymerElements/platinum-sw/blob/master/demo/index.html#L50

[davidmaxwaterman]

I implemented a solution to this, but it's not great so I'll leave this open to remind me to revisit it.