Complete WebAPI.pod (except for Examples...)
Start writing t/WebAPI.t.
WebAPI.pod: add notes about charset encoding. It's always UTF-8!!
Add Main::PSGI, a PSGI handler for Main object. Implement POST statuses and part of GET statuses.
Main::PSGI: Implement GET statuses.json and POST ack.json.
Status.pod: add a remark about status ID. it must be all in ASCII. Unicode IDs are very confusing because IDs can be both in query parameters and in body parameters. If users attempt to use Unicode IDs, BusyBird's behavior is undefined.