Removed supprot for the `DOCS_ZIPPED` artifact type now that it is removed (see ceylon/ceylon-module-resolver#107)
The "doc" tool now creates a `module-doc` folder like it would generate the .zip before: with an `api` subfolder and a `doc` subfolder if user documentation exists. The .zip file is not created anymore and no `DOCS_ZIPPED` artifact gets published (see ceylon/ceylon-module-resolver#107)
Fixed "doc" tool tests now that we don't generate a zip anymore and the API docs are now in a `api` subfolder (see ceylon/ceylon-module-resolver#107)