Bumping Ouroros API to v0.2: now with XML support and post creation!

And user auth support. Huzzah!

* Cleaned up the code a bit, some refactoring, added a wrapper class for a new post (probably useless but it looks so OO!)
* XML is supported with `XMLWriter` which means minimum PHP version required is `5.1.2` (Shimmie2 has `5.1+`)
* The post creation accepts either multipart file or attempts a transload with tons of the code copied and mangled from `ext/danbooru_api`.
 * Currently, there's no check if the user can even upload. This may or may not be a problem as this _should_ be handled by the `DataUploadEvent`-handler, will fix if this isn't the case.
* The `$this->tryAuth()` block on top of the event handler tries to populate `$user` with the current user if possible by checking either the cookies or request for user and session.