Upload reports to a GitHub repository

[marco-c]

We will create a GitHub repository where we will store the reports. Enabling gh-pages will allow people to navigate the reports easily.

[marco-c]

@rhcu this could be done separately from the crawler, so you could start with this. You can just create two fake reports to test.

The repository should have a directory for each report, and an index.html file containing links to navigate to the individual reports.
The project can:

1. Clone the repository;
2. Remove all its contents;
3. Push the new content.
   A bit like we do here: https://github.com/mozilla/release-services/blob/90ae22eb10933c5510ca529d06959194113dcdd4/src/shipit_code_coverage/shipit_code_coverage/github.py#L66.

The task is going to run on Taskcluster, so we need to set the GitHub username and password of the fake account you created as Taskcluster secrets (and you'll be able to read them as we do here: https://github.com/mozilla/release-services/blob/90ae22eb10933c5510ca529d06959194113dcdd4/src/shipit_code_coverage/shipit_code_coverage/github.py#L16). You can ask me, @La0 or @garbas for help in setting them