rspec 3 breaks passing tests

To reproduce, install rspec 3.0+ and run `rake test`. It will produce 3 failures where `be_true` and `be_false` are used when rspec 3 expects `be_truthy` and `be_falsey`.

We can:

1) lock the gem version to 2+ (as I have in this PR), or,
2) update the tests to support version 3+, which I'm happy to do on this PR if that's the preferred resolution.