v1.0.0-pre2 Release

Changes

• Update protobuf to v3.0.0
• grpc-protobuf-lite now depends on protobuf-lite. Since grpc-protobuf depends on grpc-protobuf-lite, grpc-protobuf explicitly excludes the protobuf-lite dependency and adds its own protobuf dependency. Everything should "just work" for most varieties of protobuf users, as both Maven and Gradle handle the dependencies correctly.
• Update README to every-so-slightly encourage lite instead of nano. We generally prefer lite as it is a more similar API to full protobuf, and it is the most actively maintained
• Fix a blocking unary stub bug introduced in v1.0.0-pre1 that wrapped the status in an additional status
• Minor fixes