misc: minor reorganization on devenv dockerfile

docker/devenv/Dockerfile

@@ -13,10 +13,11 @@ RUN set -ex; \
         locales \
         ca-certificates \
         wget \
-    ; \
-    rm -rf /var/lib/apt/lists/*; \
-    apt-get update -yq &&  \
-    apt-get install -yq \
+        sudo \
+        tmux \
+        vim \
+        curl \
+        zsh \
         bash \
         git \
         openjdk-8-jdk \
@@ -25,8 +26,7 @@ RUN set -ex; \
         imagemagick \
         webp \
     ; \
-    mkdir -p /etc/resolvconf/resolv.conf.d; \
-    echo "nameserver 8.8.8.8" > /etc/resolvconf/resolv.conf.d/tail; 
+    rm -rf /var/lib/apt/lists/*;
 
 RUN set -ex; \
 echo "deb http://apt.postgresql.org/pub/repos/apt/ xenial-pgdg main" >> /etc/apt/sources.list; \
@@ -35,12 +35,12 @@ RUN set -ex; \
     apt-get install -yq  \
         postgresql-9.6 \
         postgresql-contrib-9.6 \
-        sudo \
-        tmux \
-        vim \
-        curl \
-        zsh \
-    ;
+    ;\
+    rm -rf /var/lib/apt/lists/*;
+
+RUN set -ex; \
+    mkdir -p /etc/resolvconf/resolv.conf.d; \
+    echo "nameserver 8.8.8.8" > /etc/resolvconf/resolv.conf.d/tail;
 
 COPY files/pg_hba.conf /etc/postgresql/9.6/main/pg_hba.conf
 COPY files/bashrc /root/.bashrc