Converting github calls to gitlab

Emulate a gitlab CI server
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- [x] Create [web controller](https://doc.odoo.com/trunk/web/web_controllers/) to intercept GETs from gitlab
    * `"GET /{user/group}/{project}/services/gitlab_ci/{branch name} HTTP/1.1"`
- [x] Serve correct responses to gitlab impersonating Gitlab CI
- [x] Serve PUTs to simplify setup (only need to set up on runbot side)
    * `curl -X PUT "http://{gitlab_server}/api/v3/projects/{gitlab_project_id}/services/gitlab-ci" -H "PRIVATE-TOKEN: {GITLAB_TOKEN}" -d "token=NOT_USED" -d "project_url=http://{runbot_domain}/gitlab-ci/{repo_id}"`
- [x] Generate correct badges 
    * `"GET /gitlab_ci/status.png?ref=master HTTP/1.1"`
- [x] Fetch Merge requests and ignore non-starred branches