GitLab

Add environments and deployments

This MR is a continuation of https://gitlab.com/gitlab-org/gitlab-ce/issues/17009.

The current implementation is as follow:
1. We have two new tables: `environments` and `deployments`.
2. We have a new tab: `Environments` under `Pipelines` where you can see all you environments and add a new one.
3. We add a new option to `.gitlab-ci.yml` to track where we should create a deployment for environment.
4. If environment in `.gitlab-ci.yml` is specified it will create a deployment. **If environment does not exist it will be created.** (this got changed)
5. The deployment is always successful and shows the time of the action, in that case a build that presumably should do deployment. In the future we could extend deployment with statuses: success, failure. We could extend deployments with information that this is partial or full deployment.
6. User have to create environments that he will track first.
7. U...