Condense Dockerfile to optimize container size

Dockerfile

@@ -7,26 +7,18 @@
 
 FROM debian:jessie
 MAINTAINER Davey Shafik <davey@php.net>
-RUN apt-get update
-RUN apt-get update --fix-missing
-RUN echo "mysql-server mysql-server/root_password password \"''\"" | debconf-set-selections
-RUN echo "mysql-server mysql-server/root_password_again password \"''\"" | debconf-set-selections
-RUN apt-get install --yes build-essential
-RUN apt-get install --yes mysql-server postgresql
-RUN apt-get install --yes libgd-dev libxml2 libxslt1-dev libtidy-dev libreadline6 gettext libfreetype6
-RUN apt-get install --yes git
-RUN apt-get install --yes autoconf
-RUN apt-get install --yes bison re2c
-RUN apt-get install --yes openssl pkg-config libssl-dev
-RUN apt-get install --yes libbz2-dev  libcurl4-openssl-dev libenchant-dev libgmp-dev libicu-dev libmcrypt-dev postgresql-server-dev-all libpspell-dev libreadline-dev
-RUN apt-get install --yes gnupg wget
+RUN apt-get update && apt-get update --fix-missing
+RUN echo "mysql-server mysql-server/root_password password \"''\"" | debconf-set-selections && \
+    echo "mysql-server mysql-server/root_password_again password \"''\"" | debconf-set-selections
+RUN apt-get install --yes build-essential mysql-server postgresql libgd-dev libxml2 libxslt1-dev \
+    libtidy-dev libreadline6 gettext libfreetype6 git autoconf bison re2c openssl pkg-config libssl-dev \
+    libbz2-dev libcurl4-openssl-dev libenchant-dev libgmp-dev libicu-dev libmcrypt-dev \
+    postgresql-server-dev-all libpspell-dev libreadline-dev gnupg wget
 RUN ln -s /usr/include/x86_64-linux-gnu/gmp.h /usr/include/gmp.h
 
 ENV GNUPGHOME=/secure/.gnupg
 
-VOLUME /secure/.ssh
-VOLUME /secure/.gnupg
-VOLUME /php-build
+VOLUME ["/secure/.ssh", "/secure/.gnupg", "/php-build"]
 
 COPY ./build.sh /build.sh
 CMD ["/build.sh"]