Addressing exaalt/exaalt issue#2 (PSIP-CI-3). This issue requires small modifications in exaalt/parsplice AND exaalt/exaalt. In exaalt, a new docker file was created to build an image with all BASE exaalt dependencies (boost, nauty, eigen) in a simple ubuntu environment with gnu compilers. This script can be found in tools/ci_docker/dockerfile-ubuntu-base and the resulting image is stored in the registry as exaalt_ubuntu_base.  Note that this image is also used in the exaalt/parsplice yml script for continuous integration. Of courese, it is used in the exaalt/exaalt project's yml script. The gitlab-ci.yml file will test the full cmake-based build of exaalt, and will call ctest (which will pick up the simple tests in parsplice).