Added atlas-devel to docker builder.

tests/CI_docker/context/arosics_ci.docker

 FROM centos:7
 # matplotlib requires freetype, freetype-devel, libpng-devel under centos
-# scikit-image requires blas-devel lapack-devel under centos
+# scikit-image requires blas-devel, lapack-devel, atlas-devel under centos
 RUN yum update -y && \
     yum install -y wget vim bzip2 gcc gcc-c++ make libgl1-mesa-glx mesa-libGL qt5-qtbase-gui git freetype \
-        freetype-devel libpng-devel blas-devel lapack-devel
+        freetype-devel libpng-devel blas-devel lapack-devel atlas-devel
 
 ENV anaconda_dl 'Anaconda3-4.3.1-Linux-x86_64.sh'
 RUN /bin/bash -i -c "cd /root; wget https://repo.continuum.io/archive/$anaconda_dl ; \