Lock down the ability to open and close the polling period to admins only.

[mccool]

I have updated the auth rules in firebase and made the small adjustment to web.js to support users having access only to what they need and providing an admin rule.

To be an admin we just need to add admin: true to a user id. bam! access to read and write everything. (just need to test it first)

[wmbutler]

Right. Sorry, I was thinking app.js