Prepare for next development iteration
Minor Gemfile improvements

Note: `date` is not necessary anymore, it's set by default.
Rename render/renderer_opts to convert/converter_opts (fixes #2)

To be consistent with Asciidoctor.
Add spec for Diffy::Format#minitest
Fix GeneratorTask#examples_path to not be initialized with frozen array
Add and use BaseExample#content_pretty for pp to clarify API
Fix template_dirs validation in AsciidocRenderer and write specs
Rename TemplateConverterAdapter to NoFallbackTemplateConverter and write specs
Beautify generated HTML examples
Fix generator to not lose descriptions
Add integration tests using Cucumber