upgrade to Polymer 3.0?

[KiaraGrouwstra]

Polymer 3.0 hasn't reached its production release yet, allegedly still missing support for PRPL, though that seems not in use yet here (see #9). What would be the blockers for this repo to upgrade to 3.0?

[rjcorwin]

I'm super interested in this, and any way it can be dumbed down to be approachable for new comers would be great. When that's achieved, then throwing the kitchen sink at it with things like Lit HTML and Redux would be amazing.

[univhack]

@rjsteinert take a look at https://github.com/Polymer/pwa-starter-kit it's pretty helpful :)