Releasing 3.0.beta.1

Shit is still going to change a ton,
but want @avdi to be able to try it out and let me know any issues.

Also, tests are failing nondeterministically on CI right now :(
e.g. https://travis-ci.org/JoshCheek/seeing_is_believing/builds/36016132
All three rubies failed. Different places, different reasons.
None of it shows up locally t.t

So.... it's possible this release will not even work right.