Use consistent single quotes in README

Update README

sort simple_index indexes by name

This conversion is done by Transpec 2.2.5 with the following command:
    transpec

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

* 27 conversions
    from: obj.should_receive(:message)
      to: expect(obj).to receive(:message)

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

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

* 4 conversions
    from: obj.stub(:message)
      to: allow(obj).to receive(:message)

For more details: https://github.com/yujinakayama/transpec#supported-conversions

Coerce class to string for comparison

Skip "models/concerns" (since rails 4.0)

Fixes ctran/annotate_models#173, by ensuring that the model is coerced to a string before it's run through `ActiveSupport::Inflector.underscore`, which then correctly compares to the filename (which is a string already).

Update README.rdoc (gemfile git format)

don't need parentheses in if check

prevent multiple requires

[ci skip] fix whitespace