handlers.mastodon: Login using a Mastodon (or Pleroma) instance

This handler lets people log in using their Mastodon (or Mastodon-compatible) instance of choice. If someone uses a Mastodon identity to log in, it will verify their identity using the client login flow.

Simple configuration

def from_config(config):
    """ Generate a Mastodon handler from the given config dictionary.

    Posible configuration values:

    MASTODON_NAME -- the name of your website (required)
    MASTODON_HOMEPAGE -- your website's homepage (recommended)
    """