Add Api properties other than "name".

* Add path, method, contentType.
* Don't add api to container if api definition body is empty.
Moved HttpMethod to kaba.defapi.http package.
Support loading api definition from multiple files.

* When using same DslScriptHandler instance, all loaded api is added to the same container.
Reformat.
Changed defapi examples.

* At first, implement HTTP GET method.
* Add fixtures example.