Gitlab API and wrappers

Related to #3.

We are using `python-gitlab` package to interact with Gitlab APIs. When required, we are also directly using the REST APIs.

`pip install python-gitlab`

Example code:

```
import gitlab
tunnel_url = <get tunnel url from ngrok wrapper>

g_obj = gitlab.Gitlab(gitlab_url, private_token=private_token)
g_project = g_obj.projects.get(project_path)
g_project_id = g_project.get_id()

hook_params = {'push_events': True, 'pipeline_events': True, 'enable_ssl_verification': True, 'job_events': True, 'issue_events': True}
hook_params['url'] = "{0}/random-number-gitlab-incoming".format(tunnel_url)
hook_params['token'] = hashlib.sha1("some random text or url").hexdigest())

g_webhook = g_project.hooks.create (hook_params)
```

All relevant gitlab tasks or issues should be tracked under this.