ROHD-1611: Install astropy from pip

Docker/lofar-base/Dockerfile.tmpl

@@ -71,10 +71,10 @@ RUN apt-get update && apt-get upgrade -y && \
     apt-get autoclean -y && \
     apt-get -y autoremove --purge
 
-# Install numpy
+# Install numpy and astropy
 RUN export BUILD_PACKAGES="python-setuptools python-pip" && \
     apt-get install -y ${BUILD_PACKAGES} && \
-    pip install numpy && \
+    pip install numpy astropy && \
     apt-get purge -y ${BUILD_PACKAGES} && \
     apt-get clean -y && \
     apt-get autoclean -y && \