Fix #300: Add Protobuf support to Docker (#265)

Dockerfile

@@ -8,4 +8,10 @@ COPY . /var/www/html/
 # Replace `AllowOverride None` with `AllowOverride All` in `<Directory /var/www/>` in `/etc/apache2/apache2.conf`.
 RUN sed -ri -e 'N;N;N;s/(<Directory \/var\/www\/>\n)(.*\n)(.*)AllowOverride None/\1\2\3AllowOverride All/;p;d;' /etc/apache2/apache2.conf
 
+COPY --from=composer/composer:latest-bin /composer /usr/bin/composer
+RUN apt update
+RUN apt install -y git protobuf-compiler
+RUN composer require google/protobuf
+RUN protoc --php_out=proto/php/ --proto_path=proto/prototypes/ $(find proto/prototypes/ -type f)
+
 CMD apachectl -D FOREGROUND