Add support for groups that have only digits in their names and contain no alphabetic characters#467

DudyShavit wants to merge 2 commits intojenkinsci:masterjenkinsci/gitlab-branch-source-plugin:masterfrom

DudyShavit:fix/find-groupowner-by-group-idDudyShavit/gitlab-branch-source-plugin:fix/find-groupowner-by-group-idCopy head branch name to clipboard