- Directory structure follows TensorFlow.
- Rules for protobuf building are based on https://github.com/pubref/rules_protobuf, as I can't find anything simpler.
- Continuous integration with Kokoro (work in progress).

I also copied some existing Java/CC code from Bartosz and Daniel's experimental folders.

Change-Id: I7f993934d149c114320e3388fee84fbdafd7ba81