Configure jazzy

There are still a lot of issues to be solved before jazzy can be used instead of appledoc. (Tested with jazzy 0.6.0)

* No [explicit cross-references][1]
* `XCDYouTubeVideoPlayerViewController` class is _Undocumented_ because of the `#pragma clang diagnostic` surrounding it
* `-[XCDYouTubeVideo streamURLs]` documentation is buggy because of the surrounding `#if __has_feature(objc_generics)`
* Deprecated is not properly (visually) handled for `XCDYouTubeVideoQualityHD1080`
* Deprecated notification constants are not handled at all
* @discussion is not properly (visually) handled
* Empty _Type Definitions_ entry in the sidebar with a broken link
* Truncated classes and constants names in the sidebar

[1]: https://github.com/tomaz/appledoc/wiki/appledoc-docs-examples-advanced#controlling-cross-references-detection

.jazzy.yaml

@@ -0,0 +1,14 @@
+objc: true
+sdk: iphonesimulator
+source_directory: XCDYouTubeKit
+framework_root: .
+umbrella_header: XCDYouTubeKit/XCDYouTubeKit.h
+module: XCDYouTubeKit
+module_version: 2.5.2
+
+author: Cédric Luthi
+author_url: https://twitter.com/0xced
+
+readme: README.md
+github_url: https://github.com/0xced/XCDYouTubeKit
+github_file_prefix: https://github.com/0xced/XCDYouTubeKit/tree/2.5.2/XCDYouTubeKit