Update bazel version and dependencies (#22)
* Update bazel version and dependencies
- Update bazel to 3.1.0
- Upgrade bazel-based deps to work with 3.1.0
- Upgrade jar deps to newest version to avoid conflict with bazel-based deps
- Update tests, removing deprecated methods and
- Remove unneeded deps
* make test server names private
* Use official grpc-java rules for building grpc libs for java
Also removes now unneeded third party grpc rules
* Use grpc-java targets as deps rather than maven artifacts
