Include rspec-its and fix other be_truth/be_false deprecation warnings

Some basic tweaks.

---

Deprecation Warnings:

Use of rspec-core's `its` method is deprecated. Use the rspec-its gem
instead. Called from

`be_false` is deprecated. Use `be_falsey` (for Ruby's conditional
semantics) or `be false` (for exact `== false` equality) instead. Called
from

`be_true` is deprecated. Use `be_truthy` (for Ruby's conditional
semantics) or `be true` (for exact `== true` equality) instead. Called
from

78 deprecation warnings total