Modify token auth to use headers instead of query parameter

[ralphbean]

I got an email from github saying that github2fedmsg needs to modify its access token usage to send the token as a header instead of as a query parameter:

https://developer.github.com/changes/2020-02-10-deprecating-auth-through-query-param/

Apparently they are going to EOL the query parameter method near the end of this year.

[nasirhm]

I would like to work on it.