Decrease docker image size

docker/Dockerfile

@@ -18,13 +18,13 @@ RUN pip install msrest msrestazure azure-common azure-mgmt-storage azure-mgmt-co
 RUN apt-get update && apt-get install --no-install-recommends -y gcc libmysqld-dev libssl-dev libffi-dev libsqlite3-dev && \
      pip install MySQL-python && \
      pip install IM==1.6.6 && \
-     apt-get remove -y gcc libmysqld-dev libssl-dev libffi-dev libsqlite3-dev python-dev python-pip && \
-     apt-get autoremove -y && \
-     rm -rf /var/lib/apt/lists/*
+     apt-get purge -y gcc libmysqld-dev libssl-dev libffi-dev libsqlite3-dev python-dev python-pip && \
+     apt-get autoremove -y && apt-get clean && rm -rf /var/lib/apt/lists/* /tmp/* /var/tmp/* && rm -rf ~/.cache/
 
 # Remove pip requests and force python-requests to be installed to avoid SSL ca errors
 RUN pip uninstall -y requests
-RUN apt-get update && apt-get install --no-install-recommends -y python-requests && rm -rf /var/lib/apt/lists/*
+RUN apt-get update && apt-get install --no-install-recommends -y python-requests && \
+    apt-get clean && rm -rf /var/lib/apt/lists/* /tmp/* /var/tmp/* && rm -rf ~/.cache/
 
 # Copy a ansible.cfg with correct minimum values
 COPY ansible.cfg /etc/ansible/ansible.cfg