Littles adjustements

* Rakefile: esthetic
* base.rb: move options into base_options.rb
* base_options.rb: load_options method + options_example
* logger.rb: create log directory if needed
* test_helper.rb: require minitest/spec
 Add flags recognition with rake (like --no-save)
 Add failing test for BaseOptions
 Add failing tests for Rakelette
 Update gitignore