Update screenshot in readme

README.md

-# GitLab CI is an open-source continuous integration server
+## GitLab CI is an open-source continuous integration server
 * [![build status](https://secure.travis-ci.org/gitlabhq/gitlab-ci.png)](https://travis-ci.org/gitlabhq/gitlab-ci)
 * [![Code Climate](https://codeclimate.com/github/gitlabhq/gitlab-ci.png)](https://codeclimate.com/github/gitlabhq/gitlab-ci)
 * [![Dependency Status](https://gemnasium.com/gitlabhq/gitlab-ci.png)](https://gemnasium.com/gitlabhq/gitlab-ci)
 * [![Coverage Status](https://coveralls.io/repos/gitlabhq/gitlab-ci/badge.png?branch=master)](https://coveralls.io/r/gitlabhq/gitlab-ci)
-![Screen](https://github.com/downloads/gitlabhq/gitlab-ci/gitlab_ci_preview.png)
+![Screen](https://raw.github.com/gitlabhq/gitlab-ci/master/public/gitlab-ci-screenshot.png)
 ### Requirements