Consolidate the apt-get install commands

Dockerfile

@@ -4,16 +4,11 @@ MAINTAINER Taiga Authors <support@cloudron.io>
 EXPOSE 8000
 
 RUN apt-get update
-RUN apt-get install -y build-essential binutils-doc autoconf flex bison libjpeg-dev
-RUN apt-get install -y libfreetype6-dev zlib1g-dev libzmq3-dev libgdbm-dev libncurses5-dev
-RUN apt-get install -y automake libtool libffi-dev curl git tmux gettext
-
-RUN apt-get install -y python3 python3-pip python-dev python3-dev virtualenvwrapper
-RUN apt-get install -y libxml2-dev libxslt-dev
-
-RUN apt-get install -y postgresql-9.4 postgresql-contrib-9.4 postgresql-server-dev-9.4
-
-RUN apt-get install -y nginx
+RUN apt-get install -y \
+	build-essential binutils-doc autoconf flex bison libjpeg-dev libfreetype6-dev \
+	zlib1g-dev libzmq3-dev libgdbm-dev libncurses5-dev automake libtool libffi-dev curl git tmux \
+	gettext python3 python3-pip python-dev python3-dev virtualenvwrapper libxml2-dev libxslt-dev \
+	postgresql-9.4 postgresql-contrib-9.4 postgresql-server-dev-9.4 nginx
 
 WORKDIR /app/code
 
@@ -33,9 +28,10 @@ WORKDIR /app/code
 ADD build.sh /app/code/build.sh
 RUN /app/code/build.sh
 
-ADD circus.ini /app/code/circus.ini
 RUN rm /etc/nginx/sites-enabled/default
 ADD taiga.nginx.conf /etc/nginx/sites-enabled/taiga
+
+ADD circus.ini /app/code/circus.ini
 ADD conf.json /app/code/taiga-front-dist/dist/js/conf.json
 ADD local.py /app/code/taiga-back/settings/local.py
 ADD start.sh /app/code/start.sh