modernize boilerplate
activerecord 4.1 compatibility
mongoid 4 compatibility
Convert specs to RSpec 2.99.1 syntax with Transpec

This conversion is done by Transpec 2.3.6 with the following command:
    transpec -b true,false

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

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

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

* 12 conversions
    from: its(:attr) { }
      to: describe '#attr' do subject { super().attr }; it { } end

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

* 8 conversions
    from: be_false
      to: be false

* 6 conversions
    from: =~ [1, 2]
      to: match_array([1, 2])

* 5 conversions
    from: be_true
      to: be true

* 2 conversions
    from: pending 'is an example' { }
      to: skip 'is an example' { }

* 1 conversion
    from: it { should have(n).errors }
      to: it 'has n errors' do expect(subject.errors.size).to eq(n) end

* 1 conversion
    from: it { should_not ... }
      to: it { is_expected.not_to ... }

* 1 conversion
    from: lambda { }.should
      to: expect { }.to

For more details: https://github.com/yujinakayama/transpec#supported-conversions
remove deprecated tests
Fix #51 - Make sure default values read from the database are symbolized.
Ensure classes only attempt to symbolize default values for symbolized attributes defined in their class hierarchy.