Added HHVM container and used environment variable for switching

hhvm/Dockerfile

@@ -0,0 +1,21 @@
+FROM ubuntu:14.04  
+
+RUN apt-key adv --recv-keys --keyserver hkp://keyserver.ubuntu.com:80 0x5a16e7281be7a449 
+RUN apt-get update -y && apt-get install -y software-properties-common \
+   && add-apt-repository "deb http://dl.hhvm.com/ubuntu $(lsb_release -sc) main" \
+   && apt-get update -y \
+   && apt-get install -y hhvm \
+   && apt-get clean \
+   && rm -rf /var/lib/apt/lists/*
+
+RUN mkdir -p /var/www/laravel
+
+ADD server.ini /etc/hhvm/server.ini
+
+RUN usermod -u 1000 www-data
+
+WORKDIR /var/www/laravel
+
+CMD ["/usr/bin/hhvm", "-m", "server", "-c", "/etc/hhvm/server.ini"]
+
+EXPOSE 9000