Update third_party/protobuf to protobuf-v3.0.0-beta-3

third_party/protobuf/ruby/travis-test.sh

 #!/usr/bin/env bash
 
 # Exit on any error.
 set -e
 
 test_version() {
   version=$1
   if [ "$version" == "jruby" ] ; then
     # No conformance tests yet -- JRuby is too broken to run them.
     bash --login -c \
       "rvm install $version && rvm use $version && \
        which ruby && \
        gem install bundler && bundle && \
        rake test"
   else
     bash --login -c \
       "rvm install $version && rvm use $version && \
        which ruby && \
        gem install bundler && bundle && \
-       rake test"
-    # TODO(xiaofeng): Conformance tests are disabled because the ruby testee
-    # program crashes on some inputs.
-    #  cd ../conformance && \
-    #  make test_ruby
+       rake test &&
+       cd ../conformance && make test_ruby"
   fi
 }
 
 test_version $1