Create rest request and response classes

deleted:    lib/request/rest_request.dart
renamed:    lib/resource/resource.dart -> lib/resource.dart
new file:   lib/rest.dart
modified:   lib/restlet.dart
renamed:    lib/resource/resource_event.dart -> lib/src/resource/resource_event.dart
renamed:    lib/resource/resource_factory.dart -> lib/src/resource/resource_factory.dart
new file:   lib/src/rest/rest_request.dart
new file:   lib/src/rest/rest_response.dart
modified:   pubspec.yaml
new file:   test/rest_test.dart