Modify sync protcol file rules:

1. 'mvn clean compile' will (by default) force auto-sync the
kinetic.proto file (based on commit hash in the syncProtoFromRepo.sh
script) from kinetic-protocol repo and then compile/generate the Java
files.   This requires the internet connection.

2. Add a flag (-DskipProtoSync) so that the auto-sync can be disabled.
The maven command line is 'mvn clean compile -DskipProtoSync'.

3. Add a new script to get the latest protocol version from
kinetic-protocol repo.

4. Update build.setup.readme and kinetic.maven.readme.