gitlab-ci redesigned

gitla-ci totally redesigned.

Docker images are now produced on any branches including main but tags are attributed accordingly (latest for the main only and produced manually and -dev tag for others) and further tests are made on the corresponding docker image.

A R4stacomi is now produced. It is based on a ubuntu OS so that we can use c2d4u ppa which allows the installation of CRAN packages with a apt-get install packagename code. The packagename can be retrieved in the ppa: take the name under the built packages section (here r-cran-sqldf).

Test_sql is in error due to a problem in role privileges (see #11 (closed) )

Closes #16 (closed)