Fix nose coverage command, add it to GitLab CICD

Closes #933

See merge request !307

Update help message for dbfix

Closes #919

See merge request !305

Describe upgrade

See merge request !308

Delete ..db and run_unit_suite module

Closes #942

See merge request !310

Remove docs build directory

Closes #943

See merge request !309

Historic database cherry pick

See merge request es/autosubmit!312

Ready message + some bug fixes from 3.15

See merge request !311

Job_id doesn't depend on retrials anymore when is written