Update RSpec to v2.99
Fix config #persistent? methods

Because `be_true` is actually "truthy" the specs were incorrectly
passing when `"false"` was being returned uncast.
Fix RSpec deprecations
Convert specs to RSpec 2.99.1 syntax with Transpec

This conversion is done by Transpec 2.3.1 with the following command:
    transpec

* 16 conversions
    from: obj.should
      to: expect(obj).to

* 12 conversions
    from: it { should ... }
      to: it { is_expected.to ... }

* 6 conversions
    from: == expected
      to: eq(expected)

* 6 conversions
    from: lambda { }.should_not
      to: expect { }.not_to

* 5 conversions
    from: obj.should_not
      to: expect(obj).not_to

* 2 conversions
    from: Klass.any_instance.should_receive(:message)
      to: expect_any_instance_of(Klass).to receive(:message)

* 1 conversion
    from: Klass.any_instance.should_not_receive(:message)
      to: expect_any_instance_of(Klass).not_to receive(:message)

* 1 conversion
    from: mock('something')
      to: double('something')

* 1 conversion
    from: obj.unstub(:message)
      to: allow(obj).to receive(:message).and_call_original

For more details: https://github.com/yujinakayama/transpec#supported-conversions
Merge pull request #59 from brightbox/update_rspec

Update RSpec to v2.99 and fix deprecations