Minimal changes to make CBL-Ektorp work with new project structure

Updated the dependencies for the new project structure.
- Renamed the referenced CBL Maven artifact in `dependencies-archive.gradle`.
- Updated `dependencies-test.gradle` to use the new repository names and expected location (inside `libraries`).

Also separately updated the Readme to instruct users to add this inside the `libraries` folder like everything else.

I have tested the submodule case (where -java-core, -android and -android-ektorp are all included as submodules inside `libraries`) in our app and it's working for me.

I didn't try to build an archive. I'm guessing it should Just Work with the new archive name, but if you could try that with however you normally do builds before merging it would probably be for the best :smile: