fix login by using new GitHub methods

[wjwwood]

GitHub deprecated the use of access_token for queries, which this site was using, see:

https://developer.github.com/changes/2019-11-05-deprecated-passwords-and-authorizations-api/#authenticating-using-query-parameters

We were getting emails like this:

Hello there!

On February 7th, 2020 at 08:56 (UTC) your application (ROS2 Design Website) used an access token (with the User-Agent Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:72.0) Gecko/20100101 Firefox/72.0) as part of a query parameter to access an endpoint through the GitHub API.

https://api.github.com/repositories/14241623/pulls/269/files

Please use the Authorization HTTP header instead as using the `access_token` query parameter is deprecated.

Depending on your API usage, we'll be sending you this email reminder once every 3 days for each token and User-Agent used in API calls made on your behalf.
Just one URL that was accessed with a token and User-Agent combination will be listed in the email reminder, not all.

Visit https://developer.github.com/changes/2019-11-05-deprecated-passwords-and-authorizations-api/#authenticating-using-query-parameters for more information.

Thanks,
The GitHub Team

I opened #270 to disable login, until we have time to implement a new login mechanism.

[kyrofa]

We were getting emails like this:

Haha, that's one way to get people to stop using deprecated stuff. Annoy them to death.