minor change

Dockerfile

@@ -4,14 +4,14 @@ MAINTAINER Andrey Arapov <andrey.arapov@nixaid.com>
 # To avoid problems with Dialog and curses wizards
 ENV DEBIAN_FRONTEND noninteractive
 
-RUN apt-get update \
+RUN apt-get update && \
-    && apt-get install -yq apt-transport-https wget attr lsb-release \
+    apt-get -y --no-install-recommends install ca-certificates apt-transport-https wget attr lsb-release && \
-    && wget -O - https://atlassian.artifactoryonline.com/atlassian/api/gpg/key/public | apt-key add - \
+    wget -O - https://atlassian.artifactoryonline.com/atlassian/api/gpg/key/public | apt-key add - && \
-    && echo "deb https://atlassian.artifactoryonline.com/atlassian/hipchat-apt-client $(lsb_release -c -s) main" > /etc/apt/sources.list.d/atlassian-hipchat4.list \
+    echo "deb https://atlassian.artifactoryonline.com/atlassian/hipchat-apt-client $(lsb_release -c -s) main" > /etc/apt/sources.list.d/atlassian-hipchat4.list && \
-    && apt-get update \
+    apt-get update && \
-    && apt-get install -yq hipchat4 libqt5gui5 \
+    apt-get -y --no-install-recommends install hipchat4 libqt5gui5 && \
-    && apt-get -fyq install \
+    apt-get -fy --no-install-recommends install && \
-    && rm -rf -- /var/lib/apt/lists/*
+    rm -rf -- /var/lib/apt/lists/*
 
 # Make HipChat grsec friendly
 #