Add unit tests for OCTTree.

Signed-off-by: Aron Cedercrantz <aron@cedercrantz.se>
Change the order of the content class cluster.

- That is in the Xcode group, it is now in alphabetical order as most
  other things in the project.

Signed-off-by: Aron Cedercrantz <aron@cedercrantz.se>
Add OCTContent spec and stub data.

Signed-off-by: Aron Cedercrantz <aron@cedercrantz.se>