add gitlab tutorials

docs/tools/analysis.md

docs/tools/analysis/repo-include.md

docs/tools/gitlab.md

docs/tools/gitlab/1-1-tools-command-line.md

docs/tools/gitlab/1-2-tools-markdown.md

docs/tools/gitlab/1-3-tools-atom.md

docs/tools/gitlab/2-1-starting-gitlab-account.md

docs/tools/gitlab/2-2-starting-configure-git.md

docs/tools/gitlab/2-3-starting-local-repo.md

docs/tools/gitlab/2-4-starting-git-basics.md

...ools/gitlab/3-1-collaborating-stranger-or-collaborator.md

docs/tools/gitlab/3-2-collaborating-fork-their-repo.md

docs/tools/gitlab/3-3-collaborating-play-with-this-page.md

docs/tools/gitlab/4-1-you-make-your-repo.md

docs/tools/gitlab/4-2-you-doi.md

docs/tools/gitlab/4-3-you-make-your-pages-site.md

docs/tools/gitlab/5-1-projectmanagement-issues.md

docs/tools/tasks.md

img/gifs/add-contributing.gif

img/gifs/add-license.gif